Hydrogen production, carbon sequestration and heat extraction integrated method for rock mass

Abstract

This invention relates to an integrated method for hydrogen production, carbon sequestration, and heat extraction from rock masses, relating to the cross-disciplinary fields of underground energy development, geothermal utilization, and carbon sequestration. The method includes: injecting a mixed fluid into the rock mass via an injection well to induce serpentinization and carbonatization reactions within the same operating cycle; the mixed fluid comprises a circulating working fluid and carbon dioxide; the serpentinization reaction generates hydrogen and releases heat; the carbonatization reaction mineralizes and solidifies carbon dioxide and releases heat; and a collection well collects the hydrogen and recovers the reaction heat and geothermal energy from the rock mass.

Description

Technical Field

[0001] The embodiments in this specification relate to the cross-technical fields of underground energy development, geothermal utilization, and carbon sequestration, specifically to an integrated method for hydrogen production, carbon fixation, and heat extraction from rock masses. Background Technology

[0002] Basic and ultrabasic rock masses (such as peridotite, dunite, and orthopyroxene peridotite) are rich in active metal ions such as Mg and Fe. Existing technologies focus on single technologies such as hydrogen production, carbon dioxide mineralization and storage, or rock mass heat extraction, which cannot achieve the integration of multiple processes such as hydrogen production, carbon dioxide mineralization and storage, or rock mass heat extraction, resulting in serious heat waste. Summary of the Invention

[0003] The purpose of the embodiments in this specification is to provide an integrated method for hydrogen production, carbon sequestration, and heat extraction from rock masses, so as to overcome the problem that existing methods cannot achieve the integration of multiple processes such as hydrogen production, carbon dioxide mineralization and storage, or rock mass heat extraction.

[0004] To address the aforementioned technical problems, this specification provides, on the one hand, an integrated method for hydrogen production, carbon sequestration, and heat extraction from rock masses, wherein injection wells and collection wells are arranged within the rock mass; the method includes: Based on the injection well, a mixed fluid is injected into the rock mass to induce serpentinization and carbonatization reactions within the same operating cycle; the mixed fluid includes a circulating working fluid and carbon dioxide; the serpentinization reaction generates hydrogen and releases heat; the carbonatization reaction mineralizes and consolidates carbon dioxide and releases heat. Based on the acquisition well, hydrogen is collected and the exothermic reaction and geothermal energy from the rock mass are recovered.

[0005] Furthermore, the method of injecting mixed fluids into the rock mass based on the injection well to induce serpentinization and carbonatization reactions within the rock mass during the same operating cycle includes: Based on the injection well, a mixed fluid is injected into the rock mass so that the circulating working fluid reacts with the magnesium-iron silicate minerals in the rock mass to generate serpentine and magnetite and release hydrogen and heat, and causes carbon dioxide to react with alkaline earth metal ions dissolved from the rock mass to generate carbonate minerals and release heat.

[0006] Furthermore, the extraction wells include hydrogen production wells and thermal recovery wells; The process of collecting hydrogen and recovering the exothermic reaction heat and geothermal energy from the rock mass based on the acquisition well includes: Based on hydrogen-producing wells, recover multiphase fluids including hydrogen; Based on the thermal recovery well, the circulating working fluid is recovered after absorbing the heat released by the reaction and the geothermal energy of the rock mass.

[0007] Furthermore, monitoring wells are also arranged in the rock mass; the collection wells include hydrogen production wells and thermal recovery wells; the hydrogen production wells are arranged in the hydrogen accumulation zone of the rock mass or in the downstream area of ​​the fluid migration direction; the thermal recovery wells are arranged in the outer reaction zone, thermal anomaly zone or thermal breakthrough sensitive zone of the rock mass; The method further includes: Based on the monitoring well, monitoring data of the rock mass reaction zone within the current operating cycle is obtained; the monitoring data includes one or more of the following: pressure field data, chemical field data, temperature field data, resistivity data, seismic data, and tracer response data; Based on the monitoring data, the injection and production parameters of the injection well and the thermal recovery well are adjusted; the injection and production parameters include one or more of the following: injection parameters, acquisition parameters, and injection-production pressure difference between the thermal recovery well and the injection well; the injection parameters include the circulating working fluid parameters and fluid chemical parameters of the mixed fluid injected into the injection well; the acquisition parameters include the heat recovery rate of the thermal recovery well.

[0008] Furthermore, adjusting the injection and production parameters of the injection well and the thermal recovery well based on the monitoring data includes: Based on the temperature field data and the target reaction temperature ranges corresponding to the serpentinization and carbonation reactions, the heat recovery rate and circulating working fluid parameters are adjusted; the circulating working fluid parameters include one or more of the following: type of circulating working fluid, injection temperature, extraction temperature, circulating flow rate, and pressure.

[0009] Furthermore, adjusting the injection and production parameters of the injection well and the thermal recovery well based on the monitoring data further includes: Based on the pressure field data, chemical field data, and temperature field data, the dominant serpentinization reaction zone and the dominant carbonatization reaction zone in the rock mass reaction zone are identified. Based on the serpentinization reaction-dominant region and the carbonation reaction-dominant region, the fluid chemical parameters are adjusted; the fluid chemical parameters include one or more of the following: dissolved inorganic carbon concentration, metal ion concentration, pH value, redox potential, and hydrogen concentration.

[0010] Furthermore, adjusting the injection and production parameters of the injection well and the thermal recovery well based on the monitoring data further includes: Based on the pressure field data, chemical field data, and temperature field data, the dominant serpentinization reaction zone and the dominant carbonatization reaction zone in the rock mass reaction zone are identified. Based on the resistivity data and seismic data, the seepage path of the mixed fluid within the rock mass is identified; Based on the dominant zones of serpentinization and carbonation reactions and the seepage path, the heat recovery rate and circulating working fluid parameters are adjusted to control the reaction intensity of serpentinization and / or carbonation reactions; the circulating working fluid parameters include one or more of the following: type of circulating working fluid, injection temperature, production temperature, circulating flow rate, and pressure.

[0011] Furthermore, adjusting the injection and production parameters of the injection well and the thermal recovery well based on the monitoring data further includes: Based on the pressure field data, chemical field data, and temperature field data, the dominant serpentinization reaction zone and the dominant carbonatization reaction zone in the rock mass reaction zone are identified. Based on the dominant serpentinization reaction zone, the dominant carbonation reaction zone, and the target reaction temperature ranges corresponding to the serpentinization and carbonation reactions, the heat recovery rate, circulating working fluid parameters, and injection-production pressure difference are adjusted to regulate the spatial distribution of the dominant serpentinization and carbonation reaction zones, as well as the frontal expansion direction and duration of the serpentinization and carbonation reactions.

[0012] Furthermore, the mixed fluid also includes a chemical activator; the chemical activator is used to promote the dissolution of metal ions in the rock mass that participate in serpentinization and carbonatization reactions; The step of adjusting the injection and production parameters of the injection well and the thermal recovery well based on the monitoring data further includes: Organic ligands with complexing ability less than or equal to a preset complexing ability threshold are used as chemical activators under a preset long-term continuous injection strategy. If one or more of the pressure field data, chemical field data, temperature field data, resistivity data and seismic data meet the preset local activation conditions, an organic ligand with a complexing ability greater than the preset complexing ability threshold will be used as a chemical activator under the preset short-time pulse injection strategy. The preset local activation conditions include: the pressure field data, chemical field data, and temperature field data indicating that the reaction intensity of the rock mass reaction zone is lower than a preset reaction intensity threshold, or the resistivity data and seismic data indicating that the fluid transport efficiency of the seepage path is lower than a preset transport efficiency threshold.

[0013] Furthermore, adjusting the injection and production parameters of the injection well and the thermal recovery well based on the monitoring data further includes: Based on injection wells, pressure pulses are periodically applied to the rock mass to promote fracture propagation. If one or more of the pressure field data, chemical field data, temperature field data, resistivity data, and seismic data meet the preset local activation conditions, a pressure pulse is applied to the rock mass based on the injection well to promote the propagation of fractures in the rock mass; The preset local activation conditions include: the pressure field data, chemical field data, and temperature field data indicating that the reaction intensity in the reaction zone is lower than a preset reaction intensity threshold, or the resistivity data and seismic data indicating that the fluid transport efficiency of the seepage path is lower than a preset transport efficiency threshold.

[0014] Furthermore, this specification provides an integrated device for hydrogen production, carbon sequestration, and heat extraction within a rock mass, wherein an injection well and a collection well are arranged within the rock mass; the device includes: An injection module is used to inject a mixed fluid into a rock mass based on an injection well, so that the rock mass undergoes serpentinization and carbonatization reactions within the same operating cycle; the mixed fluid includes a circulating working fluid and carbon dioxide; the serpentinization reaction is used to generate hydrogen and release heat; the carbonatization reaction is used to mineralize and solidify carbon dioxide and release heat. The acquisition module is used to collect hydrogen and recover the exothermic reaction heat and geothermal energy from the rock mass based on the acquisition well.

[0015] Furthermore, embodiments of this specification provide a computer device, including: Memory, used to store computer programs; A processor is used to execute the computer program to realize the integrated method for hydrogen production, carbon fixation, and heat extraction from the aforementioned rock mass.

[0016] As can be seen from the technical solutions provided in the embodiments of this specification above, the embodiments of this specification achieve hydrogen production, carbon fixation and heat extraction simultaneously within the same rock mass and the same operating cycle, breaking through the limitations of existing technologies that are single-function and cannot be coordinated; the serpentinization reaction generates hydrogen, the carbonation reaction permanently mineralizes and solidifies carbon dioxide, and at the same time recovers the exothermic heat from the two types of reactions and the geothermal energy of the rock mass, significantly reducing heat waste and achieving efficient coupling of hydrogen production, carbon fixation and geothermal utilization. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments or prior art of this specification, the accompanying drawings used in the description of the embodiments or prior art will be briefly introduced below.

[0018] Figure 1 This is a flowchart of an integrated method for hydrogen production, carbon sequestration, and heat extraction from rock masses, provided in the embodiments of this specification. Figure 2 This is a schematic diagram of the structural composition of an integrated device for hydrogen production, carbon sequestration, and heat extraction from rock masses, provided in the embodiments of this specification. Figure 3 This is a schematic diagram of the structural composition of a computer device provided in the embodiments of this specification. Detailed Implementation

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

[0020] It should be noted that the terms "first," "second," etc., used in this specification, claims, and the foregoing drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, apparatus, product, or device that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or devices.

[0021] In some embodiments, the rock mass is a basic rock mass or an ultrabasic rock mass.

[0022] Basic rock masses can be igneous bodies with a silica content between 45% and 52%, primarily composed of pyroxene, plagioclase, and minor amounts of olivine. Common rock types include gabbro and basalt. Ultrabasic rock masses can be igneous bodies with a silica content below 45%, primarily composed of olivine and pyroxene, with almost no plagioclase. Common rock types include peridotite, dunite, pyroxene peridotite, and serpentinite. Both basic and ultrabasic rock masses are rich in magnesium and ferrous ions (total magnesium-iron minerals can reach over 70%), and in geological structures, they often occur as massive rock masses, ophiolite suites, or tectonic schists, possessing high thermal conductivity and potential for fracture development.

[0023] This specification provides an integrated method for hydrogen production, carbon sequestration, and heat extraction from rock masses, as illustrated in the embodiments below. Figure 1 As shown, the specific implementation may include the following steps: S101: Based on the injection well, a mixed fluid is injected into the rock mass to cause serpentinization and carbonatization reactions within the same operating cycle; the mixed fluid includes a circulating working fluid and carbon dioxide; the serpentinization reaction is used to generate hydrogen and release heat; the carbonatization reaction is used to mineralize and solidify carbon dioxide and release heat.

[0024] In some embodiments, injection wells and collection wells are arranged in the rock mass.

[0025] An injection well is one or more artificial boreholes that penetrate the surface into the target rock mass. Its wellbore structure includes perforations or screens in the target strata to deliver mixed fluids into the rock mass. A collection well is another one or more boreholes that also extend into the rock mass to collect products from it. This arrangement allows for a controllable pressure gradient and fluid transport pathway between the injection and collection wells.

[0026] In some embodiments, step S101 may specifically include: injecting a mixed fluid into the rock mass based on the injection well, so that the circulating working fluid reacts with magnesium-iron silicate minerals in the rock mass to generate serpentine and magnetite and release hydrogen and heat, and so that carbon dioxide reacts with alkaline earth metal ions dissolved from the rock mass to generate carbonate minerals and release heat.

[0027] The circulating working fluid can be water, supercritical carbon dioxide, or an organic heat carrier fluid, used to transfer heat and participate in the serpentinization reaction. The carbon dioxide is either gaseous or supercritical pure carbon dioxide or industrial waste gas containing carbon dioxide. After injection, the circulating working fluid undergoes a hydration reaction with magnesium-iron silicate minerals (olivine, pyroxene, etc.) in the rock mass, generating serpentine and magnetite, while releasing hydrogen and heat; this is the serpentinization reaction. The carbon dioxide then combines with alkaline earth metal ions (magnesium ions, calcium ions, ferrous ions, etc.) dissolved from the rock mass, generating magnesite, calcite, and other carbonate minerals, and releasing heat; this is the carbonatization reaction. Both types of reactions occur in parallel within the same operating cycle, without any order of priority.

[0028] In some embodiments, step S101 may further include: adjusting the partial pressure of carbon dioxide in the mixed fluid to a preset medium-high pressure range, and adjusting the initial pH of the mixed fluid to a preset weakly acidic to neutral range, so that the hydration reaction of magnesium iron silicate minerals preferentially occurs in the near-wellbore area of ​​the injection well to generate serpentine and magnetite and release hydrogen and heat; along the seepage path downstream, as carbon dioxide is consumed and pH increases, the fluid transitions to a carbonate supersaturated state, triggering the reaction of carbon dioxide with dissolved alkaline earth metal ions to generate carbonate minerals and release heat.

[0029] The partial pressure of carbon dioxide in the mixed fluid can be adjusted to a medium-high pressure range, which is a pressure range higher than the hydrostatic pressure of the rock mass but lower than the formation fracturing pressure. Simultaneously, the initial pH of the mixed fluid is adjusted to a weakly acidic to neutral range, where the pH value is greater than 5.5 and less than 7.5. Through these adjustments, in the near-wellbore region of the injection well, due to the high partial pressure of carbon dioxide and the low pH, the dissolution rate and hydration reaction of magnesium-iron silicate minerals dominate, preferentially resulting in serpentinization, generating hydrogen and releasing heat. As the mixed fluid migrates downstream along the seepage path, carbon dioxide is gradually consumed, the pH increases, and the fluid gradually transitions to a carbonate supersaturated state. In this state, carbon dioxide combines with dissolved alkaline earth metal ions to form carbonate minerals and release heat; that is, the carbonate reaction dominates in the downstream region. The two types of reactions form a continuous spatial zonation: hydrogen production upstream, carbon fixation downstream, and a transition zone in between.

[0030] In some embodiments, step S101 may further include: adopting a segmented injection strategy, first injecting a water-based fluid without carbon dioxide to induce an initial serpentinization reaction and establish an exothermic zone, and after the temperature rises to a preset range, injecting a mixed fluid containing carbon dioxide to allow carbon dioxide to enter the heated area, thereby triggering a carbonation reaction in the downstream area while maintaining the serpentinization reaction.

[0031] A staged injection strategy can be adopted. A water-based fluid, free of carbon dioxide (such as fresh water, formation water, or an aqueous solution containing low concentrations of salts), can be injected into the rock mass through an injection well to induce the initial serpentinization reaction. The initial serpentinization reaction is exothermic, gradually raising the temperature of the reaction zone to a range favorable for continued serpentinization, i.e., above the background temperature corresponding to the local geothermal gradient. Once monitoring data indicates that the temperature in the reaction zone has risen to a preset range, a mixed fluid containing carbon dioxide (10% to 50% molar fraction) is injected into the injection well. This carbon dioxide-containing fluid enters the already heated area, where the serpentinization reaction continues and exothermically, maintaining a high-temperature environment. Simultaneously, carbon dioxide migrates downstream with the fluid, triggering a carbonation reaction in the downstream area where the temperature is suitable and the pH is elevated. Both types of reactions coexist within the same operating cycle, but serpentinization mainly occurs in the heated zone and near the injection well, while carbonation mainly occurs further downstream.

[0032] S102: Based on the acquisition well, hydrogen is collected and the exothermic reaction and geothermal energy from the rock mass are recovered.

[0033] In some embodiments, the extraction well includes a hydrogen-producing well and a thermal recovery well.

[0034] The hydrogen-producing well is a borehole extending into the hydrogen-rich zone of the rock mass. It is equipped with a gas-liquid separator or gas anchor at the bottom to preferentially collect hydrogen-containing gas. The thermal recovery well is another borehole extending into the periphery of the rock mass reaction zone or thermal anomaly zone. It has a closed-loop circulation system inside its shaft to carry the circulating working fluid and extract heat. The hydrogen-producing well and the thermal recovery well are responsible for the recovery of gaseous products and heat, respectively.

[0035] In some embodiments, step S102 may specifically include: recovering a multiphase fluid including hydrogen based on a hydrogen-producing well; and recovering a circulating working fluid after absorbing the exothermic reaction and geothermal energy from the rock mass based on a thermal recovery well.

[0036] The hydrogen-producing well is connected to a gas-liquid separator at its wellhead. The bottomhole pressure is lower than the reaction zone pressure, driving a mixture of hydrogen-containing gas, water vapor, and a small amount of unreacted carbon dioxide into the wellbore and rising to the surface. The circulating working fluid, after absorbing the heat released from the reaction and geothermal energy from the rock mass, is recovered through a thermal recovery well. The thermal recovery well can employ a closed-loop circulation system. The circulating working fluid (water, supercritical carbon dioxide, or organic working fluid) absorbs heat downhole, its temperature rises, and it returns to the surface heat exchanger through the wellbore to release heat. After cooling, it is reinjected downhole. The hydrogen-producing well and the thermal recovery well operate independently.

[0037] In some embodiments, step S102 may further include: establishing a pressure linkage between the hydrogen production well and the thermal recovery well; when the heat recovery rate of the thermal recovery well increases, causing the bottom pressure of the hydrogen production well to decrease, adjusting the opening of the production valve of the hydrogen production well to maintain the pressure difference between the bottom pressure of the hydrogen production well and the pressure of the reaction zone within a preset range, so as to optimize the hydrogen recovery rate and the heat recovery rate simultaneously; adjusting the circulating working fluid flow rate of the thermal recovery well according to the hydrogen production change rate of the hydrogen production well; reducing the circulating working fluid flow rate to reduce heat removal and maintain the temperature of the reaction zone when the hydrogen production decreases; and increasing the circulating working fluid flow rate after the hydrogen production recovers.

[0038] When the heat recovery rate of a thermal recovery well increases, a local temperature drop can lead to changes in fluid viscosity, potentially causing fluctuations in the bottom hole pressure of the hydrogen production well. To address this, when the increased heat recovery rate of the thermal recovery well causes a drop in the bottom hole pressure of the hydrogen production well, the opening of the production valve can be adjusted. Reducing the valve opening increases wellbore resistance, maintaining the pressure difference between the bottom hole pressure of the hydrogen production well and the pressure in the reaction zone within a preset range, such as above 0.5 MPa and below 2 MPa. By maintaining this pressure difference, hydrogen recovery rate and heat recovery rate are optimized simultaneously. Simultaneously, the circulating fluid flow rate of the thermal recovery well is adjusted according to the rate of change in hydrogen production: when the rate of decrease in hydrogen production exceeds, for example, 5% per hour, the circulating fluid flow rate is reduced to decrease heat loss and maintain the temperature in the reaction zone; when hydrogen production recovers to, for example, more than 90% of the pre-decline level, the circulating fluid flow rate is increased.

[0039] In some embodiments, step S102 may further include: introducing the multiphase fluid produced from the hydrogen-producing well into a three-phase separator to separate it into hydrogen-rich gas, oil-containing condensate, and formation water; further purifying the hydrogen-rich gas through cryogenic separation; and reinjecting the treated formation water into the injection well; and sequentially using the high-temperature circulating working fluid produced from the hot recovery well for industrial heat load, the medium-temperature heat exchanger for district heating, and the low-temperature heat exchanger for preheating the mixed fluid in the injection well to achieve cascade utilization; and re-injecting the cooled circulating working fluid into the hot recovery well.

[0040] The three-phase separator is a horizontal or vertical pressure vessel equipped with baffles and a demister. It separates multiphase fluids into hydrogen-rich gas, oil-containing condensate, and formation water using gravity settling and centrifugal force. The hydrogen-rich gas enters a cryogenic separation unit, where it is progressively cooled to below -180 degrees Celsius. High-purity hydrogen (mole fraction greater than 99.9%) is separated by utilizing the differences in boiling points of the components. The separated formation water is filtered, deoxygenated, and pH-adjusted before being reinjected into the injection well, achieving water resource recycling. The high-temperature circulating working fluid extracted from the hot recovery well passes sequentially through a high-temperature heat exchanger, a medium-temperature heat exchanger, and a low-temperature heat exchanger. The high-temperature heat exchanger (inlet temperature 150-300 degrees Celsius) supplies industrial steam or drives a steam turbine for power generation; the medium-temperature heat exchanger (inlet temperature 80-150 degrees Celsius) is used for district heating; and the low-temperature heat exchanger (inlet temperature 30-80 degrees Celsius) preheats the mixed fluid in the injection well. The cooled circulating working fluid is then reinjected into the hot recovery well, completing a closed-loop circulation.

[0041] In some embodiments, the hydrogen is purified by a ground-based gas separation system and used for power generation, industrial fuel, or chemical feedstock.

[0042] Hydrogen-rich fluid extracted from hydrogen-producing wells is processed by a surface gas separation system to obtain purified hydrogen. This system includes membrane separators, pressure swing adsorption (PSA) towers, or cryogenic separation equipment, used to separate hydrogen from associated gases such as carbon dioxide, water vapor, and nitrogen, obtaining product hydrogen with a purity of 99.9% or higher. The purified hydrogen is then used directly for power generation (e.g., hydrogen fuel cells or gas turbine power generation), as industrial fuel (e.g., steelmaking reducing agent, glass melting burner fuel), or as a chemical raw material (e.g., ammonia synthesis, hydrodesulfurization, methanol synthesis).

[0043] In some embodiments, the recovered heat energy is used for district heating, industrial heat load, or combined heat and power.

[0044] The high-temperature circulating working fluid extracted from the thermal recovery well is cooled after releasing heat through a surface heat exchanger and then reinjected into the well. The released heat energy is utilized in stages through a heat exchange network: the high-temperature section (150°C to 300°C) is used to supply industrial heat loads (such as chemical distillation and mineral drying); the medium-temperature section (80°C to 150°C) is used for district heating systems; and the low-temperature section (30°C to 80°C) is used for combined heat and power generation through an organic Rankine cycle generator set.

[0045] In some embodiments, monitoring wells are also arranged in the rock mass; the acquisition wells include hydrogen production wells and thermal recovery wells; the hydrogen production wells are arranged in the hydrogen accumulation zone of the rock mass or in the downstream region of the fluid migration direction; the thermal recovery wells are arranged in the peripheral reaction zone, thermal anomaly zone or thermal breakthrough sensitive zone of the rock mass.

[0046] Hydrogen-producing wells are located in hydrogen accumulation zones or downstream areas of the rock mass, in the direction of fluid migration. Hydrogen accumulation zones are high-porosity fracture zones in the rock mass where gaseous hydrogen generated by serpentinization is driven upwards by buoyancy and converges. Downstream areas of fluid migration can be the farthest points reached by fluid after a long seepage path along the pressure gradient from the injection well to the hydrogen-producing well. Thermal recovery wells are located in the outer reaction zones, thermal anomaly zones, or thermal breakthrough sensitive zones of the rock mass. The outer reaction zones can be areas with large temperature gradients at the edges of serpentinization and carbonatization reaction zones. Thermal anomaly zones are areas where the monitored temperature is higher than the background geothermal temperature. Thermal breakthrough sensitive zones are areas where injected fluid may preferentially reach the thermal recovery well rapidly along high-permeability channels, causing a sharp drop in produced temperature. Monitoring wells are one or more boreholes arranged between the injection wells, hydrogen-producing wells, and thermal recovery wells. They are equipped with temperature sensors, pressure gauges, fluid sampling valves, electrode arrays, or seismic detectors to collect subsurface information without directly participating in fluid injection or product recovery. This arrangement places hydrogen-producing wells in locations where hydrogen is most easily collected, thermal recovery wells in locations where heat is most easily extracted and where early warning of thermal short circuits can be provided, and monitoring wells cover key areas between wells.

[0047] In some embodiments, injection wells are used to establish the boundary between reactants and fluid chemical inputs, hydrogen production wells are used to establish the boundary between hydrogen-rich fluid recovery, thermal recovery wells are used to establish the boundary between heat recovery and temperature control, and monitoring wells are used to provide feedback boundaries for inter-well connectivity, thermal breakthrough risk, and reaction zone evolution.

[0048] Injection wells are used to establish the chemical input boundary of reactants and fluids. This boundary can be centered on the injection well, defining the spatial extent of the initial reaction zone based on the pressure and chemical composition of the injected mixed fluid. Hydrogen-producing wells are used to establish the hydrogen-rich fluid recovery boundary. This boundary can be centered on the hydrogen-producing well, defining the spatial extent of the hydrogen and other fluid production end face through low-pressure suction at the bottom of the well. Thermal recovery wells are used to establish the heat recovery and temperature control boundary. This boundary can be centered on the thermal recovery well, defining the heat output end face and local temperature control range through the heat recovery rate and temperature of the circulating working fluid. Monitoring wells provide feedback boundaries for well connectivity, thermal breakthrough risk, and reaction zone evolution. Well connectivity refers to the degree of penetration of seepage channels in the rock mass between the injection well and the hydrogen-producing or thermal recovery well. Thermal breakthrough risk refers to the possibility that the circulating working fluid will prematurely reach the thermal recovery well along a high-permeability channel, leading to a drop in produced temperature. The evolution of the reaction zone can be the spatial movement, expansion, or contraction of the serpentinization and carbonatization reaction zones. Each boundary function is independent yet coupled through underground fluid and heat transfer. Decomposing the underground reaction engineering system into four functional units with clearly defined boundary conditions facilitates separate control of inputs, outputs, thermal management, and information feedback, achieving a balance between system decomposability and overall synergy.

[0049] In some embodiments, the above method may further include: acquiring monitoring data of the rock mass reaction zone within the current operating cycle based on the monitoring well; the monitoring data includes one or more of pressure field data, chemical field data, temperature field data, resistivity data, seismic data, and tracer response data; adjusting the injection and production parameters of the injection well and the thermal recovery well according to the monitoring data; the injection and production parameters include one or more of injection parameters, acquisition parameters, and the injection-production pressure difference between the thermal recovery well and the injection well; the injection parameters include the circulating working fluid parameters and fluid chemical parameters of the mixed fluid injected into the injection well; the acquisition parameters include the heat recovery rate of the thermal recovery well.

[0050] Monitoring data of the rock mass reaction zone during the current operating cycle can be obtained through monitoring wells. Monitoring data includes one or more of the following: pressure field data, chemical field data, temperature field data, resistivity data, seismic data, and tracer response data. Pressure field data is continuously recorded using downhole quartz manometers. Chemical field data includes the pH value, dissolved inorganic carbon concentration, metal ion (magnesium, calcium, iron) concentration, and hydrogen concentration of fluid samples, obtained through downhole fluid samplers or surface produced fluid analysis. Temperature field data is acquired through distributed fiber optic thermometry or thermocouple arrays. Resistivity data is obtained through a cross-well resistivity imaging system, reflecting fluid saturation and mineral precipitation distribution. Seismic data is recorded through downhole or surface microseismic monitoring systems to locate fracture propagation events. Tracer response data is obtained by injecting chemical or thermosensitive tracers from the injection well and detecting their breakthrough time versus concentration curves in the monitoring well and hydrogen-producing well. Based on the monitoring data, the injection and production parameters of the injection well and the thermal recovery well are adjusted. Injection and production parameters include one or more of the following: injection parameters, acquisition parameters, and the injection-production pressure differential between the thermal recovery well and the injection well. Injection parameters include the circulating working fluid parameters and fluid chemistry parameters of the mixed fluid injected into the injection well. Circulating working fluid parameters refer to the type of circulating working fluid (water, supercritical carbon dioxide, organic working fluid), injection temperature, injection pressure, and circulation flow rate. Fluid chemistry parameters refer to the mole fraction of carbon dioxide, concentration of chemical activators, and pH value in the mixed fluid. Acquisition parameters include the heat recovery rate of the thermal recovery well, i.e., the amount of heat removed from the rock mass by the circulating working fluid per unit time. The injection-production pressure difference is the difference between the bottom-hole pressure of the thermal recovery well and the bottom-hole pressure of the injection well. Adjustment methods are as follows: when temperature field data indicates that the temperature in the reaction zone deviates from the target temperature range of the serpentinization or carbonatization reaction, increase or decrease the heat recovery rate; when pressure field data indicates an abnormal increase in injection pressure, increase the injection-production pressure difference or apply a pressure pulse; when chemical field data indicates a decrease in hydrogen concentration and a simultaneous decrease in magnesium ion concentration, increase the concentration of chemical activators in the mixed fluid; when resistivity data or tracer response data indicates the presence of a preferential flow channel, adjust the injection-production pressure difference to force the fluid to bypass that channel. By utilizing complementary information from multiple types of monitoring data, real-time closed-loop adjustment of injection and heat extraction parameters can be achieved, proactively addressing the heterogeneous evolution of the underground reaction zone and extending the system's stable operation cycle.

[0051] In some embodiments, adjusting the injection and production parameters of the injection well and the thermal recovery well based on the monitoring data may further include: adjusting the heat recovery rate and circulating working fluid parameters based on the temperature field data and the target reaction temperature ranges corresponding to the serpentinization reaction and the carbonation reaction, respectively; the circulating working fluid parameters include one or more of the following: type of circulating working fluid, injection temperature, production temperature, circulating flow rate, and pressure.

[0052] Temperature field data is acquired through distributed fiber optic or thermocouple arrays deployed in monitoring wells, injection wells, and hydrogen-producing wells, reflecting the actual temperature values ​​at different locations within the rock mass reaction zone. The target reaction temperature range for serpentinization is between 200 and 300 degrees Celsius, within which the serpentinization reaction rate and hydrogen generation rate are relatively high. The target reaction temperature range for carbonatization is between 185 and 200 degrees Celsius, within which the precipitation kinetics of carbonate minerals are optimal. The heat recovery rate can be defined as the amount of heat extracted from the rock mass per unit time by the circulating working fluid in the thermal recovery well, expressed in megawatts or kilowatts. Circulating working fluid parameters include the type of circulating working fluid (water, supercritical carbon dioxide, organic working fluid), injection temperature (temperature of the circulating working fluid before entering the thermal recovery well), production temperature (temperature of the circulating working fluid returning to the surface from the thermal recovery well), circulation flow rate (volume or mass of circulating working fluid passing through the thermal recovery well per unit time), and pressure (pressure value of the circulating working fluid within the wellbore). One adjustment method is to change the heat extraction rate or circulating working fluid parameters when the temperature field data indicates that the temperature of a certain area deviates from the target range of its corresponding reaction, so that the temperature moves towards the target range.

[0053] In some embodiments, adjusting the heat harvesting rate and the circulating working fluid parameters based on the temperature field data and the target reaction temperature ranges corresponding to the serpentinization reaction and the carbonation reaction may further include: when the temperature field data indicates that the actual temperature of the reaction zone is lower than the lower limit of the target reaction temperature range of the serpentinization reaction, reducing the heat harvesting rate or suspending heat harvesting to allow the heat released by the reaction to accumulate and increase the temperature of the reaction zone.

[0054] When temperature field data indicates that the actual temperature in the reaction zone is below the lower limit of the target reaction temperature range for the serpentinization reaction, the heat recovery rate is reduced or heat recovery is suspended. The actual temperature in the reaction zone can be the average or minimum value of the rock mass temperature readings around the monitoring well or injection well. The lower limit of the target reaction temperature range for the serpentinization reaction is 200 degrees Celsius. Reducing the heat recovery rate involves decreasing the circulation flow rate of the circulating working fluid in the heat recovery well, for example, reducing the flow rate by 30% to 50% from the normal operating value. Suspending heat recovery involves completely stopping the circulation of the working fluid, putting the heat recovery well in a closed state. After the operation, the heat released by the serpentinization reaction itself is no longer carried away by the circulating working fluid, and the heat accumulates in the reaction zone, causing the rock mass temperature to gradually rise. Heat recovery is resumed after the temperature rises above 200 degrees Celsius. In low-temperature environments, priority is given to ensuring the accumulation of heat released by the serpentinization reaction, utilizing the self-heating of the reaction to raise the temperature, avoiding external heat input, and achieving energy self-sufficiency.

[0055] In some embodiments, adjusting the heat harvesting rate and the circulating working fluid parameters based on the temperature field data and the target reaction temperature ranges corresponding to the serpentinization reaction and the carbonation reaction may further include: when the temperature field data indicates that the actual temperature of the reaction zone is higher than the upper limit of the target reaction temperature range of the carbonation reaction, increasing the heat harvesting rate or increasing the injection flow rate of the circulating working fluid to accelerate heat removal and cause the temperature of the reaction zone to fall back to the target reaction temperature range of the carbonation reaction.

[0056] When temperature field data indicates that the actual temperature in the reaction zone is higher than the upper limit of the target reaction temperature range for carbonate formation, the heat recovery rate should be increased or the injection flow rate of the circulating working fluid should be increased. The upper limit of the target reaction temperature range for carbonate formation is 200 degrees Celsius. When the actual temperature is higher than 200 degrees Celsius, the carbonate precipitation rate decreases and non-target minerals may be generated. Increasing the heat recovery rate can be achieved by increasing the circulation flow rate of the circulating working fluid or by switching the circulating working fluid to a medium with a higher heat capacity (such as water instead of supercritical carbon dioxide). Increasing the injection flow rate of the circulating working fluid means increasing the frequency of the injection pump in the heat recovery well, thereby increasing the volume of working fluid flowing through the downhole heat exchange section per unit time. After accelerating the removal of heat, the temperature in the reaction zone decreases, falling back to between 185 and 200 degrees Celsius. To prevent high temperatures from inhibiting the carbonate formation reaction, the temperature is controlled within the optimal window for carbonate precipitation by enhancing heat recovery. Simultaneously, the additional recovered heat can be used for power generation or heating, improving energy gains during the high-temperature phase.

[0057] In some embodiments, the adjustment of the heat recovery rate and the circulating working fluid parameters based on the temperature field data and the target reaction temperature ranges corresponding to the serpentinization reaction and the carbonation reaction may further include: identifying high-temperature sub-regions within the reaction zone whose temperatures are higher than the upper limit of the target reaction temperature range for the serpentinization reaction, and low-temperature sub-regions whose temperatures are lower than the lower limit of the target reaction temperature range for the carbonation reaction, based on the temperature field data; adjusting the heat recovery rate and the injection direction of the circulating working fluid so that the circulating working fluid preferentially flows through the high-temperature sub-regions to enhance heat recovery, and reduces its flow through the low-temperature sub-regions to avoid excessive cooling.

[0058] Based on temperature field data, high-temperature sub-regions within the reaction zone are identified where the temperature exceeds the upper limit of the target reaction temperature range for serpentinization, and low-temperature sub-regions where the temperature falls below the lower limit of the target reaction temperature range for carbonation. High-temperature sub-regions can be localized areas with temperatures exceeding 300 degrees Celsius, where the serpentinization reaction rate may decrease due to excessively high temperatures. Low-temperature sub-regions can be localized areas with temperatures below 185 degrees Celsius, where the carbonation reaction kinetics are slow. Adjusting the heat recovery rate and the injection direction of the circulating working fluid prioritizes flow through high-temperature sub-regions to enhance heat recovery and reduces flow through low-temperature sub-regions to avoid excessive cooling. Methods for adjusting the injection direction include: installing switchable sliding sleeves or packers in the completion section of the thermal recovery well, selectively opening the wellhead of the corresponding high-temperature sub-region and closing the inlet of the corresponding low-temperature sub-region via surface control; or adjusting the pressure difference between the injection well and the thermal recovery well to prioritize fluid flow towards the high-temperature sub-region along channels with lower resistance.

[0059] In some embodiments, adjusting the heat harvesting rate and the circulating working fluid parameters based on the temperature field data and the target reaction temperature ranges corresponding to the serpentinization reaction and the carbonation reaction may further include: when the temperature field data indicates that the temperature of the reaction zone is within the target reaction temperature range of the serpentinization reaction but higher than the upper limit of the target reaction temperature range of the carbonation reaction, switching the circulating working fluid from water to supercritical carbon dioxide to reduce the heat capacity and heat harvesting intensity of the circulating working fluid, thereby lowering the temperature of the reaction zone to within the target reaction temperature range of the carbonation reaction.

[0060] When temperature field data indicates that the reaction zone temperature is within the target reaction temperature range for serpentinization but above the upper limit of the target reaction temperature range for carbonation, the circulating working fluid is switched from water to supercritical carbon dioxide. The reaction zone temperature is between 200 and 300 degrees Celsius, a temperature favorable for hydrogen production from serpentinization, but above the upper limit of the optimal temperature range for carbonation (200 degrees Celsius). The specific heat capacity of water is approximately 4,200 joules per kilogram per Kelvin, while the specific heat capacity of supercritical carbon dioxide (pressure above 7.38 MPa, temperature above 31.1 degrees Celsius) at the same temperature is approximately 800 to 1,500 joules per kilogram per Kelvin, significantly lower than that of water. After switching the circulating working fluid from water to supercritical carbon dioxide, the heat extraction intensity decreases, the heat carried away per unit volume of working fluid decreases, and the reaction zone temperature slowly decreases. Once the temperature drops below 200 degrees Celsius, a decision is made on whether to switch back to water based on demand.

[0061] In some embodiments, adjusting the injection and production parameters of the injection well and the thermal recovery well based on the monitoring data may further include: identifying the dominant serpentinization reaction zone and the dominant carbonatization reaction zone in the rock mass reaction zone based on the pressure field data, chemical field data, and temperature field data; adjusting the fluid chemical parameters based on the dominant serpentinization reaction zone and the dominant carbonatization reaction zone; wherein the fluid chemical parameters include one or more of dissolved inorganic carbon concentration, metal ion concentration, pH value, redox potential, and hydrogen concentration.

[0062] The serpentinization reaction-dominant zone can be the spatial range within the rock mass where the serpentinization reaction rate is significantly higher than the carbonatization reaction rate, and hydrogen generation is dominant in this region. The carbonatization reaction-dominant zone can be the spatial range where the carbonate mineral precipitation rate is significantly higher than the serpentinization reaction rate, and carbon dioxide mineralization and consolidation are dominant in this region. After identifying these two types of dominant zones, fluid chemical parameters are adjusted based on their spatial location, area proportion, and relative relationship. Fluid chemical parameters include dissolved inorganic carbon concentration (the total concentration of carbon dioxide, carbonate, and bicarbonate ions in the mixed fluid), metal ion concentration (magnesium ions, iron ions, calcium ions, etc.), pH value (the negative logarithm of hydrogen ion activity), redox potential (an electrochemical parameter reflecting the fluid's oxidation or reduction capacity), and hydrogen concentration (the content of dissolved or gaseous hydrogen). The adjustment methods are as follows: when the area of ​​the dominant serpentinization reaction zone is smaller than the preset ratio, the concentration of the chemical activator is increased to promote the release of metal ions; when the pH of the dominant carbonate reaction zone deviates from the suitable range for carbonate precipitation, a weak acid or weak base is added for fine-tuning; when the redox potential is too high and inhibits hydrogen generation, a reducing agent is added to lower the potential. By using the dominant reaction zone as the control target, the fluid chemical parameters are adjusted in a zoned and directional manner, avoiding interference from global adjustment to non-target areas and improving the utilization efficiency of chemical reagents.

[0063] In some embodiments, the identification of the serpentinization reaction-dominant zone and the carbonatization reaction-dominant zone in the rock mass reaction zone based on the pressure field data, the chemical field data, and the temperature field data may further include: identifying a region where the temperature is within the target reaction temperature range of the serpentinization reaction, the pH is alkaline, and the hydrogen concentration is higher than a preset high threshold as the serpentinization reaction-dominant zone; and identifying a region where the temperature is within the target reaction temperature range of the carbonatization reaction, the pH is near neutral to weakly acidic, and the dissolved inorganic carbon concentration is lower than a preset low threshold as the carbonatization reaction-dominant zone.

[0064] The serpentinization reaction is dominated by regions where the temperature is within the target reaction temperature range, the pH is alkaline, and the hydrogen concentration is above a preset high threshold. The target reaction temperature range for serpentinization is 200°C to 300°C. Alkaline pH can be defined as a pH value above 7.5. The preset high threshold is a value above the average level set based on background hydrogen concentration statistics; for example, a local hydrogen concentration exceeding three times the background value is considered high concentration. Similarly, the carbonatization reaction is dominated by regions where the temperature is within the target reaction temperature range, the pH is near-neutral to weakly acidic, and the dissolved inorganic carbon concentration is below a preset low threshold. The target reaction temperature range for carbonatization is 185°C to 200°C. Near-neutral to weakly acidic pH refers to a pH value between 5.5 and 7.5. A dissolved inorganic carbon concentration below the preset low threshold means that the concentration of carbon dioxide and related carbonate species in the fluid has decreased to a level that cannot sustain further precipitation, typically below 30% of the initial injection concentration.

[0065] In some embodiments, the identification of serpentinization-dominant and carbonatization-dominant zones in the rock mass reaction zone based on the pressure field data, the chemical field data, and the temperature field data may further include: calculating the pressure gradient distribution based on the pressure field data; identifying areas with pressure gradients higher than a preset high-pressure gradient threshold and microseismic event density higher than a preset high-density threshold as serpentinization-dominant zones; and identifying areas with pressure gradients lower than a preset low-pressure gradient threshold and permeability attenuation rate higher than a preset attenuation rate threshold as carbonatization-dominant zones.

[0066] The pressure gradient distribution is calculated based on pressure field data. The pressure gradient refers to the rate of change of pressure per unit distance, measured in megapascals per hundred meters. Regions with pressure gradients exceeding a preset high-pressure gradient threshold and microseismic event density exceeding a preset high-density threshold are identified as serpentinization-dominant zones. Serpentinization is accompanied by fluid volume expansion and hydrogen generation, leading to localized pressure increases and microfracture propagation; therefore, high-pressure gradient zones and high microseismic density zones indicate active serpentinization. The preset high-pressure gradient threshold is set at least 1.5 times the normal ground pressure gradient (approximately 0.01 megapascals per meter). Microseismic event density refers to the number of microseismic events recorded per unit volume per unit time; the preset high-density threshold is set at three times the background noise level. Regions with pressure gradients below a preset low-pressure gradient threshold and permeability decay rates exceeding a preset decay rate threshold are identified as carbonate-dominant zones. Carbonate precipitation clogs pores, leading to a decrease in pressure gradient (increased fluid flow resistance but decreased pressure drop) and permeability decay. The preset low-pressure gradient threshold is set at less than 0.5 times the normal ground pressure gradient. The penetration rate decay rate is calculated by comparing the initial penetration rate with the current penetration rate, and the preset decay rate threshold is set to be above 50%.

[0067] In some embodiments, the identification of serpentinization-dominant and carbonatization-dominant zones in the rock mass reaction zone based on the pressure field data, the chemical field data, and the temperature field data may further include: identifying the main channel between the injection well and the hydrogen-producing well based on the pressure field data; collecting fluid samples along the main channel and measuring pH and hydrogen concentration; identifying well sections with alkaline pH and hydrogen concentration above a preset high threshold as serpentinization-dominant zones, and identifying well sections with near-neutral to weakly acidic pH and hydrogen concentration below a preset low threshold as carbonatization-dominant zones.

[0068] Identify the main flow path between injection wells and hydrogen-producing wells based on pressure field data. The main flow path can be the seepage path with the largest pressure gradient and the smallest fluid resistance, determined by dense bands on pressure contour maps or the preferred breakthrough direction of tracers. Along the main flow path, collect fluid samples in segments from the hydrogen-producing wells or monitoring wells and determine pH and hydrogen concentration. Segmented sampling methods include: using downhole samplers to collect samples at different depths in horizontal or highly deviated wells, or using sliding sleeves to collect samples layer by layer in vertical wells. Well segments with alkaline pH (above 8.5) and hydrogen concentrations above a preset high threshold are identified as serpentinization reaction-dominant zones. Well segments with near-neutral to weakly acidic pH (6.0 to 7.5) and hydrogen concentrations below a preset low threshold are identified as carbonatization reaction-dominant zones. The preset high and low thresholds are taken as 150% and 50% of the average hydrogen concentration of the hydrogen-producing wells, respectively. By utilizing the vertical profile data of hydrogen-producing wells or monitoring wells, the dominant zone can be identified on a well-section basis, avoiding complex cross-well inversion and facilitating rapid decision-making for adjusting injection parameters.

[0069] In some embodiments, the above-mentioned adjustment of the fluid chemical parameters based on the identified serpentinization reaction dominance zone and carbonation reaction dominance zone may further include: when the area ratio of the serpentinization reaction dominance zone is less than a first preset ratio, increasing the concentration of the chemical activator injected into the mixed fluid to promote the dissolution of magnesium ions and iron ions and expand the range of the serpentinization reaction dominance zone.

[0070] When the area of ​​the dominant serpentinization reaction zone is less than a predetermined percentage (referred to as the first predetermined percentage), the concentration of the chemical activator in the injected mixed fluid is increased. The dominant serpentinization reaction zone refers to the spatial range within the rock mass where the serpentinization reaction rate exceeds the carbonatization reaction rate; this region is characterized by net hydrogen production. The area percentage refers to the percentage of the projected area or volume of the dominant serpentinization reaction zone to the total area or volume of the entire reaction zone. The first predetermined percentage is an empirical value, such as 30% or 40%; a percentage lower than this indicates a weaker serpentinization reaction. The chemical activator is an organic ligand solution capable of forming soluble complexes with magnesium and iron ions, such as an aqueous solution of citrate or oxalate. Its function is to weaken the metal-oxygen bonds on the surface of magnesium-iron silicate minerals, accelerating mineral dissolution. Increasing the concentration of the chemical activator increases the dissolution rate of magnesium and iron ions, exposing more fresh mineral surfaces, increasing the serpentinization reaction rate, and consequently expanding the area of ​​the dominant zone.

[0071] In some embodiments, the above-mentioned adjustment of the fluid chemical parameters based on the identified serpentinization reaction dominance zone and carbonation reaction dominance zone may further include: when the pH value in the carbonation reaction dominance zone is higher than the upper limit of pH for carbonate precipitation, adding a weak acid to the injected mixed fluid to lower the pH value and promote the precipitation of carbonate minerals.

[0072] When the pH value in the dominant carbonate reaction zone is higher than the upper limit of the suitable pH for carbonate precipitation, a weak acid is added to the injected mixed fluid to lower the pH value. The dominant carbonate reaction zone refers to the spatial range in the rock mass where the precipitation rate of carbonate minerals exceeds the serpentinization reaction rate; this region is characterized by carbon dioxide mineralization and consolidation. The pH value is the negative logarithm of the hydrogen ion activity of the fluid, reflecting the acidity or alkalinity. The upper limit of the suitable pH for carbonate precipitation refers to the highest pH value allowed for the large-scale precipitation of carbonate minerals such as magnesite and calcite, which is approximately 8.5. Above this value, the carbonate ion concentration is too high, which may lead to the formation of magnesium hydroxide precipitation instead of carbonate, or cause a decrease in the precipitation rate. The weak acid is a low-concentration organic acid (such as citric acid or acetic acid) or inorganic acid (such as carbonic acid), and its addition amount is preferably sufficient to lower the local pH value to between 7.0 and 8.0. After the pH value is lowered, the supersaturation of carbonate precipitation decreases, but the precipitation kinetics remain efficient, while avoiding competitive precipitation of hydroxides.

[0073] In some embodiments, the above-mentioned adjustment of the fluid chemical parameters based on the identified serpentinization reaction dominance zone and carbonation reaction dominance zone may further include: adjusting the dissolved inorganic carbon concentration in the injected mixed fluid according to the spatial relative positions of the serpentinization reaction dominance zone and the carbonation reaction dominance zone, so that the dissolved inorganic carbon remains below a first concentration threshold before reaching the serpentinization reaction dominance zone to avoid inhibiting the serpentinization reaction, and reaches a concentration above a second concentration threshold upon entering the carbonation reaction dominance zone to promote carbonate precipitation.

[0074] The concentration of dissolved inorganic carbon in the injected mixed fluid is adjusted based on the spatial relative positions of the serpentinization reaction-dominant zone and the carbonation reaction-dominant zone. Dissolved inorganic carbon refers to the total molar concentration of carbon dioxide, carbonate ions, and bicarbonate ions in the mixed fluid. The spatial relative position includes whether the serpentinization reaction-dominant zone is upstream, downstream, or lateral to the carbonation reaction-dominant zone. The adjustment method is as follows: the dissolved inorganic carbon concentration is kept below a certain threshold (called the first concentration threshold) before reaching the serpentinization reaction-dominant zone to avoid the potential inhibitory effect of high carbon dioxide concentration on the serpentinization reaction; when the fluid enters the carbonation reaction-dominant zone, the dissolved inorganic carbon concentration is raised above another threshold (called the second concentration threshold) to provide sufficient carbon source to promote carbonate precipitation. Methods to achieve this adjustment include: injecting fluids with different carbon dioxide concentrations in stages into the injection well, or using a downhole mixer to mix a carbon dioxide-free water-based fluid with a high-concentration carbon dioxide fluid in proportion before reaching different zones. The first concentration threshold can be set, for example, to contain less than 0.1 moles of dissolved inorganic carbon per liter of fluid, and the second concentration threshold can be set, for example, to contain more than 0.5 moles per liter.

[0075] In some embodiments, the above-mentioned adjustment of the fluid chemical parameters based on the identified serpentinization reaction dominance region and carbonation reaction dominance region may further include: when the serpentinization reaction dominance region and the carbonation reaction dominance region overlap spatially, adjusting the redox potential in the injected mixed fluid to a preset range to preferentially maintain the hydrogen generation rate of the serpentinization reaction, and adjusting the pH value to make the carbonation reaction occur at a lower rate in the overlapping region than in the non-overlapping region.

[0076] When the dominant zones of serpentinization and carbonatization overlap spatially, the redox potential in the injected mixed fluid is adjusted to a preset range, and the pH value is controlled to cause the carbonatization reaction to occur at a lower rate in the overlapping zone than in the non-overlapping zone. Spatial overlap refers to the simultaneous detection of high-activity indicators of serpentinization and carbonatization within the same rock mass volume, such as temperature being within the target range for both types of reactions, pH fluctuating near neutral, and both hydrogen and magnesium ion concentrations being at moderate levels. Redox potential is an electrochemical parameter reflecting the oxidation or reduction capacity of a fluid, measured in millivolts. The preset range is a reducing environment, i.e., a redox potential below -200 millivolts. Under these conditions, the hydrogen generation rate in the serpentinization reaction is high, while the carbonatization reaction is not sensitive to redox potential but is significantly affected by pH. The adjustment method involves adding a reducing agent (such as sodium thiosulfate or sodium sulfite) to the mixed fluid to lower the redox potential; simultaneously, by adding a trace amount of weak acid, the pH value of the overlapping zone is maintained between 6.5 and 7.5, reducing the carbonate precipitation rate by approximately 30% to 50% from the optimal value (pH 8.0 to 8.5), while maintaining a relatively high serpentinization reaction rate. In regions where the two types of reactions cannot be spatially separated, the competitive interference of carbonate formation on serpentinization is actively suppressed through dual electrochemical and acid-base regulation, prioritizing hydrogen generation while allowing a certain degree of carbon fixation to avoid completely sacrificing the carbon fixation function.

[0077] In some embodiments, adjusting the injection and production parameters of the injection well and the thermal recovery well based on the monitoring data may further include: identifying the dominant serpentinization reaction zone and the dominant carbonatization reaction zone in the rock mass reaction zone based on the pressure field data, chemical field data, and temperature field data; identifying the seepage path of the mixed fluid in the rock mass based on the resistivity data and seismic data; and adjusting the heat recovery rate and circulating working fluid parameters based on the dominant serpentinization reaction zone, the dominant carbonatization reaction zone, and the seepage path to control the reaction intensity of the serpentinization reaction and / or the carbonatization reaction; wherein the circulating working fluid parameters include one or more of the following: type of circulating working fluid, injection temperature, production temperature, circulating flow rate, and pressure.

[0078] Resistivity data, obtained through a cross-well resistivity imaging system, reflects the ability of different locations in the rock mass to impede electric current, measured in ohmmeters. When a mixed fluid (a mixture of water, carbon dioxide, and chemical activators) fills pores or fractures, the resistivity is lower than in dry or mineral-filled areas. Microseismic data, recorded through in-well or surface geophone arrays, reflects the elastic waves released when the rock fractures; the spatial location and density of microseismic events indicate the degree of fracture development. The specific operation for identifying seepage paths involves identifying continuous regions in the resistivity imaging where the resistivity is below a preset threshold (called the first resistivity threshold) as the main flow channels for the mixed fluid. The first resistivity threshold is set based on the background resistivity of the undisturbed rock mass, for example, one-third of the background resistivity. Simultaneously, linear bands in the microseismic data where the microseismic event density is above a preset threshold (called the first density threshold) are identified as fracture propagation directions. The first density threshold is three times the background microseismic event density. The region where the main flow channel overlaps with the linear band is determined as the seepage path.

[0079] In some embodiments, the identification of the seepage path of the mixed fluid in the rock mass based on the resistivity data and the microseismic data may further include: identifying a continuous region in the resistivity imaging with a resistivity lower than a first resistivity threshold as the main flow channel of the mixed fluid, identifying a linear band in the microseismic data with a microseismic event density higher than a first density threshold as the direction of fracture propagation, and determining the region where the main flow channel overlaps with the linear band as the seepage path.

[0080] The fluid front advancement path can be the region where the mixed fluid has just arrived and is expanding the seepage range, where fluid saturation is increasing. The precipitation blockage path can be a region where pores or fractures are gradually closed due to carbonate or silicate precipitation, obstructing fluid flow and causing a decrease in permeability. The identification method involves acquiring time-shifted resistivity imaging data and microseismic event location data within the same time period, and then overlaying and analyzing them in three-dimensional space. Time-shifted resistivity imaging refers to resistivity data volumes collected at different time points, reflecting the rate of change of resistivity over time through comparison. Regions where resistivity decreases over time and microseismic events are active are identified as fluid front advancement paths. Decreasing resistivity indicates fluid filling, and active microseismic events indicate fracture expansion; both jointly indicate outward advancement of the seepage region. Regions where resistivity increases over time and microseismic events are sparse are identified as precipitation blockage paths. Increased resistivity indicates that conductive fluid is being replaced by high-resistivity precipitates, and sparse microseismic events indicate no new fracture formation.

[0081] In some embodiments, the seepage path may include a fluid front propagation path and a sedimentation blockage path. The above-described identification of the seepage path of the mixed fluid within the rock mass based on the resistivity data and the microseismic data may further include: spatially overlaying resistivity imaging data and microseismic event location data within the same time period, identifying regions where resistivity decreases over time and microseismic events are active as fluid front propagation paths, and identifying regions where resistivity increases over time and microseismic events are sparse as sedimentation blockage paths.

[0082] Acquire time-lapse resistivity imaging data and calculate the resistivity change rate between two adjacent time points. The resistivity change rate refers to the change in resistivity per unit time; a negative value indicates a decrease in resistivity (fluid inflow), and a positive value indicates an increase in resistivity (precipitation or drying). Regions with resistivity change rates below a preset threshold (called the second resistivity threshold) are identified as fast-flowing channels in the seepage path. Below the second resistivity threshold indicates a rapid rate of resistivity decrease, indicating that fluid is rapidly passing through the region. The second resistivity threshold is set to -5% per month. Simultaneously, obtain the focal mechanism solution for microseismic events. The focal mechanism solution determines the orientation of the rupture surface and the direction of the principal stress by analyzing the initial motion direction of the microseismic waveform. Strips where the principal stress direction coincides with the extension direction of regions with resistivity change rates below the second resistivity threshold, and where microseismic events are concentrated, are identified as the main channels of the seepage path. The main channels are high-permeability channels where fluid preferentially flows, extending along the direction of the maximum principal stress.

[0083] In some embodiments, the identification of the seepage path of the mixed fluid in the rock mass based on the resistivity data and the microseismic data may further include: acquiring time-shifted resistivity imaging data, calculating the resistivity change rate at two adjacent time points, identifying regions with resistivity change rates below a second resistivity threshold as rapid fluid channels in the seepage path; acquiring the focal mechanism solution of microseismic events, and identifying strips where the principal stress direction is consistent with the extension direction of regions with resistivity change rates below the second resistivity threshold and where microseismic events are concentrated as the main channels of the seepage path.

[0084] The three-dimensional resistivity model obtained from resistivity data inversion is jointly inverted with the three-dimensional fracture density model obtained from microseismic data inversion. Resistivity inversion can reconstruct the three-dimensional distribution of subsurface resistivity using potential difference data measured at the surface or between wells through numerical algorithms. Microseismic event inversion refers to using the travel time and amplitude data of microseismic waves to infer the source location and fracture density (the area or volume fraction of fractures per unit volume). Joint inversion can simultaneously optimize the two types of data under the same objective function to obtain a unified model that simultaneously fits resistivity and microseismic response. In the joint inversion results, three-dimensional connected structures formed by connecting volume elements with resistivity below a preset threshold (called the third resistivity threshold) and fracture density above another preset threshold (called the second density threshold) are identified as seepage paths of mixed fluids. The third resistivity threshold is taken as half of the background resistivity, and the second density threshold is taken as twice the background fracture density.

[0085] In some embodiments, the identification of the seepage path of the mixed fluid in the rock mass based on the resistivity data and the microseismic data may further include: jointly inverting the three-dimensional resistivity model obtained by inverting the resistivity data and the three-dimensional fracture density model obtained by inverting the microseismic data, and identifying the three-dimensional connected structure formed by connecting volume elements with resistivity lower than a third resistivity threshold and fracture density higher than a second density threshold as the seepage path of the mixed fluid.

[0086] When the seepage path primarily traverses the dominant serpentinization reaction zone, and the reaction intensity in this zone is below a preset intensity threshold (referred to as the first intensity threshold), the heat recovery rate is reduced or the injection temperature of the circulating working fluid is increased. Reaction intensity is characterized by the rate of change in hydrogen production or the rate of magnesium ion release. The first intensity threshold is set at 60% of the normal operating value. Reducing the heat recovery rate involves decreasing the circulating flow rate of the working fluid or switching to a low-heat-capacity medium (such as supercritical carbon dioxide replacing water). Increasing the injection temperature of the circulating working fluid means preheating it to above ambient temperature using a surface heater before injection to reduce heat absorption from the rock mass. These operations reduce heat loss, allow for the accumulation of exothermic serpentinization, increase the temperature in the reaction zone, and enhance the intensity of the serpentinization reaction.

[0087] In some embodiments, adjusting the heat recovery rate and the circulating working fluid parameters according to the identified serpentinization reaction dominance zone, carbonation reaction dominance zone, and seepage path may further include: when the seepage path mainly passes through the serpentinization reaction dominance zone and the reaction intensity of the serpentinization reaction dominance zone is lower than a first intensity threshold, reducing the heat recovery rate or increasing the injection temperature of the circulating working fluid to reduce heat loss and increase the temperature of the reaction zone, thereby enhancing the serpentinization reaction intensity.

[0088] When the seepage path primarily traverses the dominant carbonatization reaction zone, and the reaction intensity in this zone falls below a preset intensity threshold (referred to as the second intensity threshold), the heat recovery rate is increased or the injection temperature of the circulating working fluid is decreased. The carbonatization reaction intensity is characterized by the carbon dioxide consumption rate or the carbonate mineral precipitation rate. The second intensity threshold is taken as 70% of the normal operating value. Increasing the heat recovery rate involves increasing the circulation flow rate of the circulating working fluid or switching to a high-heat-capacity medium (such as water replacing supercritical carbon dioxide). Decreasing the injection temperature of the circulating working fluid refers to cooling the working fluid before injection using a surface cooler to increase its ability to absorb heat from the rock mass. The carbonatization reaction rate decreases when the temperature exceeds its optimal range (185°C to 200°C). Enhanced heat recovery prevents excessively high temperatures, allowing the temperature in the reaction zone to return to the optimal range and maintaining the carbonatization reaction intensity.

[0089] In some embodiments, the above-mentioned adjustment of the heat recovery rate and the circulating working fluid parameters based on the identified serpentinization reaction dominance zone, carbonation reaction dominance zone, and seepage path may further include: when the seepage path mainly passes through the carbonation reaction dominance zone and the reaction intensity of the carbonation reaction dominance zone is lower than a second intensity threshold, increasing the heat recovery rate or decreasing the injection temperature of the circulating working fluid to remove excess reaction heat, prevent the temperature from exceeding the target reaction temperature range of the carbonation reaction, thereby maintaining the carbonation reaction intensity.

[0090] When the seepage path passes through both the serpentinization reaction-dominant zone and the carbonate reaction-dominant zone, and the serpentinization reaction-dominant zone is upstream and the carbonate reaction-dominant zone is downstream along the seepage path direction, the circulating working fluid is adjusted to water and the circulation flow rate is increased. Water has a high specific heat capacity (approximately 4,200 joules per kilogram of Kelvin), effectively carrying heat. Increasing the circulation flow rate means increasing the injection rate of the circulating working fluid in the thermal recovery well to two to three times the normal value. The exothermic reaction in the upstream serpentinization zone raises the temperature of the circulating working fluid. As the high-temperature working fluid flows downstream along the seepage path, it transfers heat to the carbonate reaction-dominant zone, raising the temperature in that area to the optimal carbonate reaction range.

[0091] In some embodiments, the above-mentioned adjustment of the heat recovery rate and the circulating working fluid parameters based on the identified serpentinization reaction dominance zone, carbonation reaction dominance zone, and seepage path may further include: when the seepage path passes through both the serpentinization reaction dominance zone and the carbonation reaction dominance zone, and the serpentinization reaction dominance zone is located upstream and the carbonation reaction dominance zone is located downstream along the seepage path direction, adjusting the circulating working fluid to water and increasing the circulating flow rate to accelerate the introduction of serpentinization reaction exothermic heat into the downstream carbonation reaction dominance zone, thereby promoting the carbonation reaction intensity.

[0092] When multiple branches exist in the seepage path, where the first branch mainly flows through the serpentinization reaction-dominant zone and the second branch mainly flows through the carbonatization reaction-dominant zone, the heat recovery rate of the thermal recovery well and the distribution ratio of the circulating working fluid in each branch are adjusted. A branch refers to a flow path originating from the injection well, passing through different seepage channels to reach the same or different thermal recovery wells. Adjustment methods for the distribution ratio include: installing switchable sliding sleeves in the completion section of the thermal recovery well to selectively open the corresponding branch section; or using segmented injection in the injection well to allow different branches to obtain different flow rates of circulating working fluid. The adjustment objective is to prioritize the flow of the circulating working fluid through branches where the reaction intensity is below a preset threshold. The preset threshold is set to 50% of the normal operating intensity of each reaction type.

[0093] In some embodiments, the adjustment of the heat recovery rate and the circulating working fluid parameters based on the identified serpentinization reaction dominance zone, carbonation reaction dominance zone, and seepage path may further include: when there are multiple branches in the seepage path, and the first branch mainly flows through the serpentinization reaction dominance zone and the second branch mainly flows through the carbonation reaction dominance zone, adjusting the heat recovery rate of the thermal recovery well and the distribution ratio of the circulating working fluid in each branch, so that the circulating working fluid preferentially flows through the branch with reaction intensity lower than a preset threshold, so as to balance the overall intensity of the two types of reactions.

[0094] Time-shifted resistivity imaging and microseismic monitoring were used to identify fast-flow channels, leading-edge propagation zones, and blockage zones in the seepage path. Temperature and chemical field data were combined to delineate the serpentinization and carbonation reaction-dominant zones. When a blockage zone was located within the serpentinization reaction-dominant zone and the reaction intensity decreased in that zone, short-duration pulsed chemical activators (such as EDTA) and pressure pulses were injected directionally into the blockage zone to restore the seepage channel. When a fast-flow channel bypassed the carbonation reaction-dominant zone, resulting in a lack of fluid supply to that zone, the injection-production pressure differential was increased and the sliding sleeve opening position of the thermal recovery well was adjusted, forcing some fluid to divert into the carbonation reaction-dominant zone. Simultaneously, the heat recovery rate was adjusted according to the temperature distribution along the seepage path to match the heat release from the upstream serpentinization reaction with the heat demand from the downstream carbonation reaction.

[0095] In some embodiments, adjusting the injection and production parameters of the injection well and the thermal recovery well based on the monitoring data may further include: identifying the dominant serpentinization reaction zone and the dominant carbonatization reaction zone in the rock mass reaction zone based on the pressure field data, chemical field data, and temperature field data; and adjusting the heat recovery rate, circulating working fluid parameters, and injection-production pressure difference based on the dominant serpentinization reaction zone, the dominant carbonatization reaction zone, and the target reaction temperature ranges corresponding to the serpentinization reaction and the carbonatization reaction, so as to adjust the spatial distribution of the dominant serpentinization reaction zone and the dominant carbonatization reaction zone, the frontal extension direction of the serpentinization reaction and the carbonatization reaction, and the duration.

[0096] Based on the identified two dominant zones and the target reaction temperature ranges corresponding to serpentinization and carbonatization reactions, the heat recovery rate, circulating working fluid parameters, and injection-production pressure differential are adjusted. Adjusting these parameters alters the temperature and flow fields of the reaction zone, thereby modifying the spatial distribution of the dominant serpentinization and carbonatization reaction zones, the direction of the frontal extension of the two reaction types, and their duration. Spatial distribution refers to the location and extent of the dominant zone within the three-dimensional rock mass. The direction of frontal extension refers to the outward advancement of the reaction zone boundary. Duration refers to the length of time a particular reaction type maintains its dominant position in a specific area.

[0097] In some embodiments, the above-mentioned adjustment of the heat recovery rate, the circulating working fluid parameters, and the injection-production pressure difference based on the identified serpentinization reaction dominance zone, the carbonation reaction dominance zone, and the target reaction temperature ranges corresponding to the serpentinization reaction and the carbonation reaction respectively may further include: when the serpentinization reaction dominance zone is located upstream of the carbonation reaction dominance zone and the two meet a preset adjacent condition, increasing the heat recovery rate and increasing the injection-production pressure difference to accelerate the downstream migration of heat, causing the temperature of the carbonation reaction dominance zone to rise to its target reaction temperature range, thereby expanding the spatial range of the carbonation reaction dominance zone.

[0098] When the serpentinization reaction zone is located upstream of the carbonate reaction zone, and both meet a preset adjacency condition, the heat recovery rate is increased and the injection-production pressure differential is raised. Upstream refers to a location closer to the injection well along the fluid migration direction. The preset adjacency condition means the minimum distance between the boundaries of the two main zones is less than a preset value, such as less than 50 meters, indicating a close spatial connection. The heat recovery rate is increased by increasing the circulation flow rate of the working fluid in the thermal recovery well, or by switching the working fluid to a high-heat-capacity medium (such as water replacing supercritical carbon dioxide). The injection-production pressure differential is raised by increasing the injection pressure in the injection well or decreasing the bottomhole pressure in the thermal recovery well, expanding the pressure differential to 150% of its normal value. These operations accelerate the migration of heat from the upstream serpentinization reaction zone downstream, causing the temperature in the carbonate reaction zone to rise to the range of 185°C to 200°C. With the temperature increase, the carbonate reaction rate increases, and the spatial extent of this main zone expands further downstream.

[0099] In some embodiments, the above-mentioned adjustment of the heat recovery rate, the circulating working fluid parameters, and the injection-production pressure difference based on the identified serpentinization reaction-dominant zone, the carbonation reaction-dominant zone, and the target reaction temperature ranges corresponding to the serpentinization reaction and the carbonation reaction respectively may further include: when the reaction front extension direction of the serpentinization reaction-dominant zone deviates from the preset direction, reducing the heat recovery rate and switching the circulating working fluid to supercritical carbon dioxide, and reducing the injection-production pressure difference to reduce the heat extraction intensity in the downstream region, so that the serpentinization reaction-dominant zone extends to a lower-temperature lateral region.

[0100] When the reaction front extension direction of the serpentine reaction-dominant zone deviates from the preset direction, the heat recovery rate is reduced and the circulating working fluid is switched to supercritical carbon dioxide, while the injection-production pressure differential is decreased. The reaction front extension direction is determined by a time-shifted temperature field or hydrogen concentration distribution map. The preset direction is the pre-designed direction of reaction zone advancement, such as uniform expansion from the injection well to the surrounding areas or directional advancement along a specific fracture zone. Deviation refers to an angle greater than 30 degrees between the actual extension direction and the preset direction. The heat recovery rate is reduced by decreasing the circulating flow rate of the working fluid to less than 50% of the normal value. Switching the circulating working fluid to supercritical carbon dioxide (pressure above 7.38 MPa, temperature above 31.1 degrees Celsius) has a lower heat capacity than water, resulting in a decrease in heat recovery intensity. The injection-production pressure differential is reduced by decreasing the injection pressure of the injection well or increasing the bottom hole pressure of the thermal recovery well, reducing the pressure differential to 50% of the normal value. The above operations reduce the heat extraction intensity in the downstream area, allowing more heat from the reaction zone to remain upstream and laterally, causing the serpentine reaction-dominant zone to extend into the lower-temperature lateral region, thereby correcting the deviated advancement direction.

[0101] In some embodiments, the above-mentioned adjustment of the heat recovery rate, the circulating working fluid parameters, and the injection-production pressure difference based on the identified serpentinization reaction dominance zone, the carbonation reaction dominance zone, and the target reaction temperature ranges corresponding to the serpentinization reaction and the carbonation reaction, may further include: when the serpentinization reaction dominance zone and the carbonation reaction dominance zone overlap spatially and the temperature of the overlapping area is between the target reaction temperature ranges of the two, the heat recovery rate and the injection-production pressure difference are adjusted alternately, first increasing the heat recovery rate and decreasing the injection-production pressure difference to preferentially maintain the carbonation reaction, and then decreasing the heat recovery rate and increasing the injection-production pressure difference to restore the serpentinization reaction, so that the two types of reactions in the overlapping area alternately dominate in time, extending the overall coordinated operation time.

[0102] When the dominant serpentinization reaction zone and the dominant carbonatization reaction zone spatially overlap, and the temperature of the overlapping area falls between the target reaction temperature ranges of the two zones, the heat recovery rate and injection-production pressure differential are adjusted alternately. Spatial overlap can be achieved when high-activity indicators of both types of reactions are detected simultaneously within the same rock mass volume, such as moderate levels of hydrogen concentration and magnesium ion consumption rate. The temperature of the overlapping area is between 200 degrees Celsius (lower limit of the serpentinization range) and 185 degrees Celsius (upper limit of the carbonatization range), i.e., between 185 degrees Celsius and 200 degrees Celsius. At this temperature, both types of reactions may occur, but neither is optimal. The alternating adjustment method is as follows: first, increase the heat recovery rate and decrease the injection-production pressure differential, and run for a period of time (e.g., 24 to 72 hours) to lower the temperature of the overlapping area to around 185 degrees Celsius, preferentially maintaining the carbonatization reaction (lower temperatures are more conducive to carbonate precipitation); then, decrease the heat recovery rate and increase the injection-production pressure differential, and run for the same period to raise the temperature back to around 200 degrees Celsius, restoring the dominance of the serpentinization reaction. This cycle repeats continuously, allowing the two types of reactions in the overlapping region to alternately dominate in time. In regions where the two types of reactions cannot be spatially separated, a time-sharing multiplexing strategy allows hydrogen production and carbon fixation to proceed alternately, avoiding long-term mutual inhibition and ensuring that both functions can be realized, thus extending the overall coordinated operation time.

[0103] In some embodiments, the above-mentioned adjustment of the heat recovery rate, the circulating working fluid parameters, and the injection-production pressure difference based on the identified serpentinization reaction-dominant zone, the carbonation reaction-dominant zone, and the target reaction temperature ranges corresponding to the serpentinization reaction and the carbonation reaction respectively may further include: when the advancing speed of the leading edge of the serpentinization reaction-dominant zone is higher than that of the leading edge of the carbonation reaction-dominant zone, increasing the heat recovery rate and switching the circulating working fluid from water to a low-heat-capacity organic working fluid, while simultaneously increasing the injection-production pressure difference, so as to preferentially extract heat from the leading edge of the serpentinization reaction, reduce its advancing speed, and keep the leading edges of the two types of reactions advancing synchronously.

[0104] When the advance velocity of the serpentinization reaction front is higher than that of the carbonate reaction front, the heat recovery rate should be increased and the circulating working fluid should be switched from water to a low-heat-capacity organic working fluid, while simultaneously increasing the injection-production pressure differential. The advance velocity is calculated by dividing the distance the reaction zone boundary moves in the time-shifted temperature field or chemical concentration field by time, in meters per day. A higher advance velocity at the serpentinization reaction front than at the carbonate reaction front will cause the hydrogen production zone to expand too rapidly while the carbon fixation zone lags behind, ultimately resulting in hydrogen escaping beyond the carbon fixation coverage area. Increasing the heat recovery rate involves doubling the circulating flow rate of the working fluid. Switching to a low-heat-capacity organic working fluid (such as isobutane or pentane), with a specific heat capacity of approximately 2 kilojoules per kilogram per Kelvin (half that of water), can compensate for this by increasing the flow rate at the same flow rate. Low-heat-capacity working fluids are more easily heated within the wellbore, thus efficiently extracting heat from the serpentinization reaction front. The injection-production pressure differential can be increased by raising the injection well pressure or lowering the thermal recovery well pressure, expanding the differential to 180% of its normal value. This operation prioritizes extracting heat from the serpentinization reaction front to lower its local temperature and slow its advance. Simultaneously, the extracted heat is carried downstream by the circulating working fluid, indirectly promoting the advancement of the carbonation reaction front, thus aligning the advance rates of the two types of reactions.

[0105] In some embodiments, the mixed fluid further includes a chemical activator; the chemical activator is used to promote the dissolution of metal ions involved in serpentinization and carbonatization reactions in the rock mass. Based on this, the above-mentioned adjustment of injection and production parameters of injection wells and thermal recovery wells according to the monitoring data may further include: using organic ligands with complexing capacity less than or equal to a preset complexing capacity threshold as chemical activators under a preset long-term continuous injection strategy; if one or more of the pressure field data, chemical field data, temperature field data, resistivity data, and seismic data meet preset local activation conditions, using organic ligands with complexing capacity greater than a preset complexing capacity threshold as chemical activators under a preset short-time pulse injection strategy; wherein, the preset local activation conditions include: the pressure field data, chemical field data, and temperature field data indicating that the reaction intensity of the rock mass reaction zone is lower than a preset reaction intensity threshold, or, the resistivity data and seismic data indicating that the fluid transport efficiency of the seepage path is lower than a preset transport efficiency threshold.

[0106] Chemical activators are organic ligand solutions capable of forming soluble complexes with metal ions such as magnesium, iron, and calcium ions. Their function is to promote the dissolution of metal ions involved in serpentinization and carbonatization reactions within the rock mass. When adjusting injection and production parameters of injection wells and hot recovery wells based on monitoring data, the following strategy is adopted: organic ligands with a complexing capacity less than or equal to a preset threshold (called the preset complexing capacity threshold) are used as chemical activators under a long-term continuous injection strategy. Complexing capacity refers to the equilibrium constant for the organic ligand to form stable complexes with metal ions; a larger value indicates a stronger complexing capacity. The preset complexing capacity threshold is used to distinguish between weakly complexing ligands (such as citrate and oxalate) and strongly complexing ligands (such as EDTA and DTPA). Long-term continuous injection refers to continuously adding chemical activators to the injection well at a constant or slowly varying concentration throughout the entire operating cycle. When one or more of the pressure field data, chemical field data, temperature field data, resistivity data, and microseismic data meet preset local activation conditions, organic ligands with a complexing capacity greater than a preset complexing capacity threshold are used as chemical activators under the short-time pulse injection strategy. The preset local activation conditions include two categories: the first category is that the pressure field data, chemical field data, and temperature field data indicate that the reaction intensity in the rock mass reaction zone is lower than a preset reaction intensity threshold (e.g., hydrogen production drops to less than 50% of normal); the second category is that the resistivity data and microseismic data indicate that the fluid transport efficiency of the seepage path is less than a preset transport efficiency threshold (e.g., tracer breakthrough time is extended to more than twice the initial value). Short-time pulse injection refers to injecting a strong complexing ligand at a high concentration over a short period (tens of minutes to several hours) and then stopping. By automatically switching the chemical activator type and injection mode according to the underground reaction state, weak ligands are used to maintain baseline activity under normal conditions, and strong ligands are used for targeted repair in case of failure, balancing economy and effectiveness.

[0107] In some embodiments, the above-mentioned use of organic ligands with complexing capacity less than or equal to a preset complexing capacity threshold as chemical activators under a long-term continuous injection strategy may further include: selecting citrate ions as the organic ligand and continuously injecting them at a first preset concentration to continuously complex magnesium and iron ions on the surface of the rock mass and maintain the activity of the reaction interface.

[0108] Citrate ions were chosen as the organic ligand. Citrate ions are the anions formed by the dissociation of citric acid in aqueous solution, with the chemical formula C6H5O7. 3- Its complexation stability constant with magnesium and iron ions is moderate (approximately 10). 6(Scale). Continuous injection at a first preset concentration. The first preset concentration is a predetermined value, for example, 0.01 to 0.1 moles of citrate per liter of mixed fluid. Continuous injection refers to the continuous addition of this concentration of citrate to the mixed fluid in the injection well without interruption. Citrate continuously binds to magnesium and iron ions on the rock surface through complexation, weakening the metal-oxygen bonds on the mineral surface, promoting mineral dissolution, maintaining the activity of the reaction interface, and preventing excessive growth of the surface passivation layer. Citrate is a biodegradable and environmentally friendly ligand; long-term low-concentration injection will not pollute the formation and can effectively inhibit the formation of silicate passivation layers, extending the efficient reaction cycle of serpentinization and carbonatization.

[0109] In some embodiments, the use of organic ligands with complexing capacity less than or equal to a preset complexing capacity threshold as chemical activators under a long-term continuous injection strategy may further include: selecting oxalate ions as the organic ligands and continuously injecting them at a second preset concentration to promote magnesium silicate dissolution under near-neutral pH conditions without inhibiting carbonate precipitation.

[0110] Oxalate ions were chosen as the organic ligand. Oxalate ions are the anions formed by the dissociation of oxalic acid in aqueous solution, with the chemical formula C₂O₄. 2- Oxalate has a moderate complexing ability with magnesium ions and a certain complexing effect on calcium ions. It is continuously injected at a second preset concentration, for example, 0.005 mol / L. Oxalate effectively promotes the dissolution of magnesium silicate minerals under near-neutral pH conditions (pH 6.0 to 7.5) without significantly inhibiting carbonate precipitation. This is because the complex formed between oxalate and magnesium ions can still dissociate and release magnesium ions to participate in magnesite formation under carbonate supersaturation conditions. Oxalate promotes magnesium dissolution without disrupting the chemical balance required for carbonate precipitation, avoiding the inability of magnesium ions to precipitate due to excessive complexation.

[0111] In some embodiments, the use of organic ligands with complexing capacity less than or equal to a preset complexing capacity threshold as chemical activators under a long-term continuous injection strategy may further include: adjusting the injection concentration of the organic ligand according to the metal ion concentration in the monitoring data; increasing the organic ligand concentration when the magnesium ion concentration is lower than a third preset concentration; and decreasing the organic ligand concentration when the magnesium ion concentration is higher than a fourth preset concentration, in order to maintain the balance between the metal ion release rate and the carbonate precipitation rate.

[0112] Metal ion concentration refers to the molar concentration of magnesium, iron, and calcium ions in the produced fluid or monitoring well fluid. Monitoring data is acquired in real time through downhole fluid samplers or surface produced fluid analysis. When the magnesium ion concentration is below a preset threshold (referred to as the ninth threshold), the injected concentration of the organic ligand is increased. The ninth threshold is, for example, 0.001 mol / L; below this value indicates insufficient mineral dissolution rate. Increasing the injected concentration, for example, by increasing the citrate concentration from 0.01 mol / L to 0.05 mol / L. When the magnesium ion concentration is above another preset threshold (referred to as the tenth threshold), the injected concentration of the organic ligand is decreased. The tenth threshold is, for example, 0.01 mol / L; above this value indicates excessively rapid dissolution, potentially exceeding the carbonate precipitation capacity. Decreasing the injected concentration, for example, by restoring it to 0.01 mol / L. Through dynamic adjustment, a balance is maintained between the metal ion release rate and the carbonate precipitation rate.

[0113] In some embodiments, the above-mentioned use of organic ligands with complexing capacity less than or equal to a preset complexing capacity threshold as chemical activators under a long-term continuous injection strategy may further include: selecting a mixed ligand of citrate and oxalate, and continuously injecting it at a fifth preset concentration to simultaneously promote the selective release of iron and magnesium ions, wherein citrate preferentially complexes iron ions and oxalate preferentially complexes magnesium ions.

[0114] A mixed ligand of citrate and oxalate is selected. The mixed ligand refers to the dissolution of two organic ligands in the same injection fluid at a specific molar ratio. Citrate preferentially complexes iron ions (with a higher stability constant), while oxalate preferentially complexes magnesium ions (with better selectivity for magnesium). Continuous injection is performed at a fifth preset concentration, for example, a total concentration of 0.02 to 0.08 mol / L, where the molar ratio of citrate to oxalate is 1:0.5 to 1:2. This mixed ligand simultaneously promotes the selective release of both iron and magnesium ions: iron ions, after being complexed by citrate, participate in magnetite formation, which is beneficial for serpentinization; magnesium ions, after being complexed by oxalate, are released and can be used for subsequent carbonate precipitation.

[0115] In some embodiments, the use of an organic ligand with a complexing capacity greater than the preset complexing capacity threshold as a chemical activator under a short-time pulse injection strategy may further include: selecting EDTA as an organic ligand, and injecting it at a sixth preset concentration for a first preset time in a pulse manner when the injection-production pressure difference is detected to rise above a preset pressure difference threshold or the hydrogen production rate drops above a preset production rate threshold, in order to rapidly complex iron and calcium ions in the blockage, dissolve the precipitate layer, and restore permeability.

[0116] EDTA (ethylenediaminetetraacetic acid) was chosen as the organic ligand. EDTA is a strong complexing agent, with complexation stability constants as high as 10 for calcium, magnesium, and iron ions. 10 Up to 10 25Quantity. At a sixth preset concentration (e.g., 0.05 to 0.2 mol per liter), injection is performed in a pulsed manner for a first preset time when specific conditions are detected. Specific conditions include: the injection-production pressure difference rising above a preset pressure difference threshold (e.g., 1.5 times the normal pressure difference), or hydrogen production decreasing above a preset production threshold (e.g., 30% of normal production). Pulsed injection refers to continuous injection over a short period (the first preset time is one to six hours), followed by cessation. The injected EDTA rapidly complexes iron and calcium ions in the blockage, dissolves the carbonate precipitate and silicate passivation layer, and restores permeability.

[0117] In some embodiments, the use of an organic ligand with a complexing capacity greater than the preset complexing capacity threshold as a chemical activator under a short-time pulse injection strategy may further include: selecting DTPA (diethylenetriaminepentaacetic acid) as an organic ligand, injecting it at a preset pulse frequency at a seventh preset concentration when the tracer response data indicates that precipitation blockage has occurred in the preferred flow channel, for selectively removing the silicon-rich surface layer and re-exposing the fresh reaction surface.

[0118] DTPA (diethylenetriaminepentaacetic acid) was chosen as the organic ligand. DTPA is similar to EDTA but has a stronger complexing ability, and its stability constants for calcium and magnesium ions are about an order of magnitude higher than EDTA. At a seventh preset concentration (e.g., 0.02 mol to 0.1 mol per liter), it was injected at a preset pulse frequency when the tracer response data indicated precipitation blockage in the preferred flow channel. The preset pulse frequency was, for example, once every seven days, lasting two hours each time. The tracer response data included prolonged tracer breakthrough time and decreased peak concentration. DTPA can selectively remove the silica-rich surface layer (by complexing surface iron and magnesium, causing disintegration of the silicate framework) and re-expose fresh reaction surfaces.

[0119] In some embodiments, the use of organic ligands with complexing capacity greater than the preset complexing capacity threshold as chemical activators under the short-time pulse injection strategy may further include: identifying the spatial location of the blockage area based on resistivity imaging data in the monitoring data, preparing a composite pulse activator by mixing EDTA and oxalic acid at a first preset molar ratio, and injecting it directionally into the blockage area through an injection well, with the injection duration being proportional to the volume of the blockage area, for the purpose of locally dissolving carbonate precipitates and silicate passivation layers within a second preset time.

[0120] The spatial location of the blockage area is identified based on resistivity imaging data from monitoring data. The resistivity imaging data is used to obtain a three-dimensional resistivity distribution through time-shift inversion; the blockage area exhibits a high resistivity anomaly (because both carbonates and serpentine are high-resistivity minerals). A composite pulse activator is prepared by mixing EDTA and oxalic acid at a preset molar ratio (referred to as the first preset molar ratio, e.g., 1:1). EDTA in the composite pulse activator provides strong complexing ability to dissolve carbonate precipitates, while oxalic acid provides a mild dissolving effect on silicates. This is then directionally injected into the blockage area through injection wells. Directional injection methods include: using packers to isolate non-target well sections and pressurizing injection only into the perforated section corresponding to the blockage area. The injection duration is proportional to the volume of the blockage area, for example, injecting 0.5 cubic meters of activator per cubic meter of blockage volume. The carbonate precipitates and silicate passivation layer are locally dissolved within a second preset time (e.g., fifteen minutes to two hours).

[0121] In some embodiments, the use of organic ligands with complexing capacity greater than the preset complexing capacity threshold as chemical activators under the short-time pulse injection strategy may further include: after the short-time pulse injection is completed, injecting a neutral flushing fluid that does not contain organic ligands, wherein the volume of the flushing fluid is greater than the pulse injection volume, for pushing the dissolved metal ion complexes and stripped precipitate particles toward the hydrogen production well or thermal recovery well, thereby avoiding secondary blockage caused by reprecipitation.

[0122] Following a short pulse injection, a neutral flushing fluid free of organic ligands is injected. This neutral flushing fluid is water or formation water with a pH of 6.5 to 7.5, and contains no complexing agents. The volume of the flushing fluid is larger than the pulse injection volume, for example, 1.5 to 3 times the pulse injection volume. The purpose of the flushing fluid is to push dissolved metal ion complexes and precipitates stripped from the rock surface toward the hydrogen-producing well or thermal recovery well, preventing these substances from redepositing in the near-wellbore area and causing secondary blockage. The injection pressure of the flushing fluid is maintained at the same level as the normal injection pressure.

[0123] In some embodiments, adjusting the injection and production parameters of the injection well and the thermal recovery well based on the monitoring data may further include: periodically applying pressure pulses to the rock mass based on the injection well to promote fracture propagation in the rock mass; if the pressure field data, chemical field data, temperature field data, resistivity data, and seismic data meet preset local activation conditions, applying pressure pulses to the rock mass based on the injection well to promote fracture propagation in the rock mass; wherein the preset local activation conditions include: the pressure field data, chemical field data, and temperature field data indicating that the reaction intensity of the reaction zone is lower than a preset reaction intensity threshold, or the resistivity data and seismic data indicating that the fluid transport efficiency of the seepage path is lower than a preset transport efficiency threshold.

[0124] A pressure pulse refers to a momentary or short-term increase in pressure at the injection wellhead or downhole that is higher than the normal injection pressure, which lasts for a period of time before returning to normal or decreasing. Simultaneously, if pressure field data, chemical field data, temperature field data, resistivity data, and microseismic data meet preset local activation conditions, a pressure pulse is also applied to the rock mass based on the injection well.

[0125] In some embodiments, the above-mentioned application of pressure pulses to the rock mass based on the injection well may further include: injecting a mixed fluid at a constant pressure for a third preset time within each first preset cycle, then increasing the injection pressure to a level greater than the constant pressure and maintaining it for a fourth preset time, then decreasing the injection pressure to a level less than the constant pressure and maintaining it for a fourth preset time, repeating the pressure increase and decrease cycle multiple times to induce the periodic expansion and closure of microfractures.

[0126] Within each fixed time period (referred to as the first preset cycle), a mixed fluid is injected at a constant pressure for a period of time (referred to as the third preset time). The constant pressure is the normal injection pressure, for example, two to five MPa higher than the pore pressure of the rock mass. The third preset time is, for example, twelve hours. Subsequently, the injection pressure is increased to a value higher than the constant pressure (for example, 1.5 times the constant pressure) and maintained for a shorter period of time (referred to as the fourth preset time, for example, five minutes). Then, the injection pressure is decreased to a value lower than the constant pressure (for example, 0.5 times the constant pressure) and maintained for the same fourth preset time. This pressure increase-decrease cycle is repeated multiple times, for example, three to five times. This periodic pressure change causes microfractures to open during pressure increase and partially close during pressure decrease, inducing repeated tensile and compressive stresses on the fracture walls, promoting the periodic expansion and closure of fractures, and preventing excessive fracture penetration caused by unidirectional expansion.

[0127] In some embodiments, the above-mentioned application of pressure pulses to the rock mass based on the injection well may further include: injecting at a constant pressure within the first fifth preset time period of each second preset cycle, and applying a sinusoidal pressure pulse within the second sixth preset time period to generate a fatigue propagation effect in the fracture network and increase the fracture density.

[0128] Within each fixed time period (referred to as the second preset cycle, e.g., seven days), normal injection is performed at a constant pressure for the preceding period (referred to as the fifth preset period, e.g., six days). A sinusoidal pressure pulse is then applied for the following period (referred to as the sixth preset period, e.g., one day). The sinusoidal pressure pulse refers to an injection pressure that varies sinusoidally over time, with an amplitude of ±30% of the constant pressure and a frequency, for example, between 0.1 Hz and 1 Hz. This high-frequency, low-amplitude pressure fluctuation generates alternating stress in the fracture network, causing repeated micrometer-level displacement of the fracture walls. This leads to cohesive fatigue failure between mineral particles, thereby inducing new microcracks around existing fractures, increasing fracture density without significantly increasing the width of the main fracture.

[0129] In some embodiments, the above-mentioned application of pressure pulses to the rock mass based on the injection well may further include: automatically adjusting the period and amplitude of the pressure pulses according to the frequency of microseismic events in the monitoring data; shortening the pulse period and increasing the pulse amplitude when the frequency of microseismic events is lower than a first event threshold; and extending the pulse period and decreasing the pulse amplitude when the frequency of microseismic events is higher than a second event threshold, so that the fracture propagation rate is maintained within a preset range.

[0130] The pressure pulse period and amplitude are automatically adjusted based on the frequency of microseismic events in the monitoring data. The microseismic event frequency refers to the number of microseismic events recorded per unit time, measured in units per day. When the microseismic event frequency is below a preset threshold (called the first event threshold, e.g., ten events per day), it indicates that the fracture is expanding slowly or has stopped. In this case, the pulse period is shortened (e.g., from seven days to three days) and the pulse amplitude is increased (e.g., the pressure is increased from 1.5 times the constant pressure to twice the constant pressure) to enhance the stimulation intensity. When the microseismic event frequency is above another preset threshold (called the second event threshold, e.g., one hundred events per day), it indicates that the fracture is expanding too rapidly, potentially forming a large crack that could cause a fluid short circuit. In this case, the pulse period is extended (e.g., from seven days to fourteen days) and the pulse amplitude is decreased (e.g., from 1.5 times to 1.2 times the constant pressure) to maintain the fracture expansion rate within a preset range (e.g., expansion of 0.5 meters to 2 meters per day).

[0131] In some embodiments, the above-mentioned application of pressure pulses to the rock mass based on the injection well may further include: adding solid proppant with a particle diameter smaller than a preset diameter threshold to the mixed fluid during each pressurization phase of the pressure pulse, so that the proppant enters the newly expanded microfractures with the fluid; and stopping the addition of proppant during the depressurization phase to prevent the fractures from closing completely and to maintain the permeability after expansion.

[0132] During each pressurization phase of the pressure pulse, a solid proppant is added to the mixed fluid. The solid proppant is ceramic particles, quartz sand, or resin-coated sand with a particle diameter smaller than a preset diameter threshold (e.g., fifty micrometers). The proppant is carried by the high-pressure fluid into newly expanded microfractures and is carried deeper as the fractures open. Propant addition is stopped during the depressurization phase. As pressure decreases, the fractures tend to close, but the proppant particles prop open the fracture walls, preventing complete closure and maintaining the expanded permeability. This cyclical operation of adding proppant during pressurization and stopping during depressurization ensures that proppant is injected only when the fractures open, avoiding waste in unexpanded pores.

[0133] In some embodiments, the aforementioned preset local activation conditions may further include: the pressure field data indicates that the injection pressure of the injection well continuously rises above a first pressure threshold at a constant injection rate and lasts for a duration exceeding a first duration, and the microseismic data indicates that the frequency of microseismic events is lower than a first frequency threshold; when the condition is met, a single pressure pulse with a first pressure increase rate and a first peak pressure is applied to the injection well to forcibly open the fracture that was blocked by precipitation.

[0134] When pressure field data indicates that the injection pressure of the injection well continuously rises above a pressure threshold (referred to as the first pressure threshold) at a constant injection rate and lasts for a duration exceeding a time threshold (referred to as the first duration), and microseismic data indicates that the frequency of microseismic events is below a frequency threshold (referred to as the first frequency threshold), it is determined that fracture blockage due to precipitation has occurred. The first pressure threshold is, for example, 1.2 times the normal injection pressure. The first duration is, for example, six hours. The first frequency threshold is, for example, one event per hour. When this condition is met, a single pressure pulse is applied through the injection well. This pulse has a pressure rise rate (referred to as the first pressure rise rate, for example, 0.5 MPa to 1.0 MPa per minute) and a peak pressure (referred to as the first peak pressure, for example, two to 2.5 times the normal injection pressure). This pulse is not cyclical; it rapidly rises to high pressure in one go and then immediately depressurizes to forcibly open fractures blocked by carbonate or silicate precipitation.

[0135] In some embodiments, the aforementioned preset local activation conditions may further include: the resistivity data indicates that the resistivity of a certain segment in the seepage path rises above a third resistivity threshold in two consecutive time-shift imaging sessions, and the microseismic data indicates that there are no microseismic events in that segment; when this condition is met, a directional pressure pulse is applied to the well segment corresponding to that segment through the injection well; after the directional pressure pulse isolates the non-target segment through the packer, it is pressurized to the fracturing pressure of the formation in that segment at a preset pressurization rate, so as to locally destroy the carbonate deposit layer and restore the seepage channel.

[0136] When resistivity data indicates that the resistivity of a segment within the seepage path rises above a resistivity threshold (referred to as the third resistivity threshold, e.g., twice the background resistivity) in two consecutive time-shifted imaging sessions, and microseismic data indicates no microseismic events within that segment (microseismic event density is zero or below the background noise level), it is determined that a carbonate deposit has blocked the segment without spontaneous rupture. When this condition is met, a directional pressure pulse is applied to the corresponding well section through the injection well. After isolating the non-target segment via a packer, the directional pressure pulse is pressurized at a certain rate (e.g., 1.0 MPa to 2.0 MPa per minute) to the rupture pressure of the formation in that segment (estimated through adjacent wells or empirical formulas). The pressure concentrates in the blocked segment, locally disrupting the carbonate deposit and restoring the seepage channel.

[0137] In some embodiments, the aforementioned preset local activation condition may further include: the pressure field data indicating that the injection-production pressure difference between the injection well and the thermal recovery well continues to expand beyond a second pressure threshold under constant injection conditions, and the tracer response data indicating that the tracer breakthrough time is extended beyond the initial breakthrough time; when this condition is met, a pulse sequence consisting of multiple sub-pulses is applied through the injection well to induce the fracture network to reconnect through fatigue loading.

[0138] When pressure field data indicates that the injection-production pressure differential between the injection well and the thermal recovery well continuously increases beyond a pressure threshold (referred to as the second pressure threshold, e.g., 1.5 times the normal pressure differential) under constant injection conditions, and tracer response data indicates that the tracer breakthrough time is prolonged beyond the initial breakthrough time (e.g., from the initial 24 hours to more than 72 hours), the main channel is considered blocked. When this condition is met, a pulse sequence consisting of multiple sub-pulses is applied through the injection well. Each sub-pulse has a pressurization time of several minutes, a holding time of several minutes, and a depressurization time of several minutes; the number of sub-pulses is three to five. The continuous action of multiple sub-pulses induces the reconnection of the fracture network around the blocked area through a fatigue loading mechanism, without requiring a single excessively high pressure.

[0139] As can be seen from the technical solutions provided in the embodiments of this specification above, the embodiments of this specification achieve hydrogen production, carbon fixation and heat extraction simultaneously within the same rock mass and the same operating cycle, breaking through the limitations of existing technologies that are single-function and cannot be coordinated; the serpentinization reaction generates hydrogen, the carbonation reaction permanently mineralizes and solidifies carbon dioxide, and at the same time recovers the exothermic heat from the two types of reactions and the geothermal energy of the rock mass, significantly reducing heat waste and achieving efficient coupling of hydrogen production, carbon fixation and geothermal utilization.

[0140] Based on the above-mentioned integrated method for hydrogen production, carbon sequestration, and heat extraction from rock masses, this specification also proposes embodiments of an integrated device for hydrogen production, carbon sequestration, and heat extraction from rock masses. For example... Figure 2 As shown, the integrated hydrogen production, carbon sequestration, and heat extraction device 200 for the rock mass may specifically include the following modules: Injection module 201 is used to inject a mixed fluid into the rock mass based on an injection well, so that the rock mass undergoes serpentinization and carbonatization reactions within the same operating cycle; the mixed fluid includes a circulating working fluid and carbon dioxide; the serpentinization reaction is used to generate hydrogen and release heat; the carbonatization reaction is used to mineralize and solidify carbon dioxide and release heat. The acquisition module 202 is used to acquire hydrogen and recover reaction exothermics and geothermal energy from the rock mass based on the acquisition well.

[0141] In some embodiments, the injection of mixed fluids into the rock mass based on the injection well to induce serpentinization and carbonatization reactions within the rock mass during the same operating cycle includes: Based on the injection well, a mixed fluid is injected into the rock mass so that the circulating working fluid reacts with the magnesium-iron silicate minerals in the rock mass to generate serpentine and magnetite and release hydrogen and heat, and causes carbon dioxide to react with alkaline earth metal ions dissolved from the rock mass to generate carbonate minerals and release heat.

[0142] In some embodiments, the extraction well includes a hydrogen production well and a thermal recovery well; The process of collecting hydrogen and recovering the exothermic reaction heat and geothermal energy from the rock mass based on the acquisition well includes: Based on hydrogen-producing wells, recover multiphase fluids including hydrogen; Based on the thermal recovery well, the circulating working fluid is recovered after absorbing the heat released by the reaction and the geothermal energy of the rock mass.

[0143] In some embodiments, monitoring wells are also arranged in the rock mass; the acquisition wells include hydrogen production wells and thermal recovery wells; the hydrogen production wells are arranged in the hydrogen accumulation zone of the rock mass or in the downstream area of ​​the fluid migration direction; the thermal recovery wells are arranged in the peripheral reaction zone, thermal anomaly zone or thermal breakthrough sensitive zone of the rock mass; The integrated hydrogen production, carbon sequestration, and heat extraction device 200 for the rock mass is also used for: Based on the monitoring well, monitoring data of the rock mass reaction zone within the current operating cycle is obtained; the monitoring data includes one or more of the following: pressure field data, chemical field data, temperature field data, resistivity data, seismic data, and tracer response data; Based on the monitoring data, the injection and production parameters of the injection well and the thermal recovery well are adjusted; the injection and production parameters include one or more of the following: injection parameters, acquisition parameters, and injection-production pressure difference between the thermal recovery well and the injection well; the injection parameters include the circulating working fluid parameters and fluid chemical parameters of the mixed fluid injected into the injection well; the acquisition parameters include the heat recovery rate of the thermal recovery well.

[0144] In some embodiments, adjusting the injection and production parameters of the injection well and the thermal recovery well based on the monitoring data includes: Based on the temperature field data and the target reaction temperature ranges corresponding to the serpentinization and carbonation reactions, the heat recovery rate and circulating working fluid parameters are adjusted; the circulating working fluid parameters include one or more of the following: type of circulating working fluid, injection temperature, extraction temperature, circulating flow rate, and pressure.

[0145] In some embodiments, adjusting the injection and production parameters of the injection well and the thermal recovery well based on the monitoring data further includes: Based on the pressure field data, chemical field data, and temperature field data, the dominant serpentinization reaction zone and the dominant carbonatization reaction zone in the rock mass reaction zone are identified. Based on the serpentinization reaction-dominant region and the carbonation reaction-dominant region, the fluid chemical parameters are adjusted; the fluid chemical parameters include one or more of the following: dissolved inorganic carbon concentration, metal ion concentration, pH value, redox potential, and hydrogen concentration.

[0146] In some embodiments, adjusting the injection and production parameters of the injection well and the thermal recovery well based on the monitoring data further includes: Based on the pressure field data, chemical field data, and temperature field data, the dominant serpentinization reaction zone and the dominant carbonatization reaction zone in the rock mass reaction zone are identified. Based on the resistivity data and seismic data, the seepage path of the mixed fluid within the rock mass is identified; Based on the dominant zones of serpentinization and carbonation reactions and the seepage path, the heat recovery rate and circulating working fluid parameters are adjusted to control the reaction intensity of serpentinization and / or carbonation reactions; the circulating working fluid parameters include one or more of the following: type of circulating working fluid, injection temperature, production temperature, circulating flow rate, and pressure.

[0147] In some embodiments, adjusting the injection and production parameters of the injection well and the thermal recovery well based on the monitoring data further includes: Based on the pressure field data, chemical field data, and temperature field data, the dominant serpentinization reaction zone and the dominant carbonatization reaction zone in the rock mass reaction zone are identified. Based on the dominant serpentinization reaction zone, the dominant carbonation reaction zone, and the target reaction temperature ranges corresponding to the serpentinization and carbonation reactions, the heat recovery rate, circulating working fluid parameters, and injection-production pressure difference are adjusted to regulate the spatial distribution of the dominant serpentinization and carbonation reaction zones, as well as the frontal expansion direction and duration of the serpentinization and carbonation reactions.

[0148] In some embodiments, the mixed fluid further includes a chemical activator; the chemical activator is used to promote the dissolution of metal ions in the rock mass that participate in serpentinization and carbonatization reactions; The step of adjusting the injection and production parameters of the injection well and the thermal recovery well based on the monitoring data further includes: Organic ligands with complexing ability less than or equal to a preset complexing ability threshold are used as chemical activators under a preset long-term continuous injection strategy. If one or more of the pressure field data, chemical field data, temperature field data, resistivity data and seismic data meet the preset local activation conditions, an organic ligand with a complexing ability greater than the preset complexing ability threshold will be used as a chemical activator under the preset short-time pulse injection strategy. The preset local activation conditions include: the pressure field data, chemical field data, and temperature field data indicating that the reaction intensity of the rock mass reaction zone is lower than a preset reaction intensity threshold, or the resistivity data and seismic data indicating that the fluid transport efficiency of the seepage path is lower than a preset transport efficiency threshold.

[0149] In some embodiments, adjusting the injection and production parameters of the injection well and the thermal recovery well based on the monitoring data further includes: Based on injection wells, pressure pulses are periodically applied to the rock mass to promote fracture propagation. If one or more of the pressure field data, chemical field data, temperature field data, resistivity data, and seismic data meet the preset local activation conditions, a pressure pulse is applied to the rock mass based on the injection well to promote the propagation of fractures in the rock mass; The preset local activation conditions include: the pressure field data, chemical field data, and temperature field data indicating that the reaction intensity in the reaction zone is lower than a preset reaction intensity threshold, or the resistivity data and seismic data indicating that the fluid transport efficiency of the seepage path is lower than a preset transport efficiency threshold.

[0150] As can be seen from the technical solutions provided in the embodiments of this specification above, the embodiments of this specification achieve hydrogen production, carbon fixation and heat extraction simultaneously within the same rock mass and the same operating cycle, breaking through the limitations of existing technologies that are single-function and cannot be coordinated; the serpentinization reaction generates hydrogen, the carbonation reaction permanently mineralizes and solidifies carbon dioxide, and at the same time recovers the exothermic heat from the two types of reactions and the geothermal energy of the rock mass, significantly reducing heat waste and achieving efficient coupling of hydrogen production, carbon fixation and geothermal utilization.

[0151] This specification also provides a computer device for an integrated method of hydrogen production, carbon sequestration, and heat extraction from rock masses, including a processor and a memory for storing processor-executable instructions. Specifically, the processor can perform the following tasks according to the instructions: injecting a mixed fluid into the rock mass based on an injection well, so that the rock mass undergoes serpentinization and carbonatization reactions within the same operating cycle; the mixed fluid includes a circulating working fluid and carbon dioxide; the serpentinization reaction generates hydrogen and releases heat; the carbonatization reaction mineralizes and solidifies carbon dioxide and releases heat; and based on a collection well, collecting hydrogen and recovering the reaction heat and geothermal energy from the rock mass.

[0152] To execute the above instructions more accurately, please refer to... Figure 3 As shown in the embodiments of this specification, another specific computer device 300 is also provided, wherein the computer device 300 includes a network communication port 301, a processor 302 and a memory 303, and the above structures are connected by internal cables so that the various structures can perform specific data interaction.

[0153] The processor 302 can be specifically used to: inject a mixed fluid into the rock mass based on an injection well, so that the rock mass undergoes serpentinization and carbonatization reactions within the same operating cycle; the mixed fluid includes a circulating working fluid and carbon dioxide; the serpentinization reaction is used to generate hydrogen and release heat; the carbonatization reaction is used to mineralize and solidify carbon dioxide and release heat; and based on a collection well, collect hydrogen and recover the reaction heat and geothermal energy from the rock mass.

[0154] The memory 303 can be used to store the corresponding instruction program.

[0155] In this embodiment, the network communication port 301 can be a virtual port bound to different communication protocols, thereby enabling the sending or receiving of different data. For example, the network communication port can be a port responsible for web data communication, a port responsible for FTP data communication, or a port responsible for email data communication. Furthermore, the network communication port can also be a physical communication interface or communication chip. For example, it can be a wireless mobile network communication chip, such as GSM or CDMA; it can also be a Wi-Fi chip; or it can be a Bluetooth chip.

[0156] In this embodiment, the processor 302 can be implemented in any suitable manner. For example, the processor can take the form of a microprocessor or processor and a computer-readable medium storing computer-readable program code (e.g., software or firmware) executable by the (micro)processor, logic gates, switches, application-specific integrated circuits (ASICs), programmable logic controllers, and embedded microcontrollers, etc. This specification is not limiting.

[0157] In this embodiment, the memory 303 includes volatile memory and non-volatile memory. The memory 303 can include multiple layers. In digital systems, anything that can store binary data can be a memory; in integrated circuits, a circuit with storage function but no physical form is also called a memory, such as RAM, FIFO, etc.; in a system, a storage device with a physical form is also called a memory, such as a memory stick, TF card, etc.

[0158] Furthermore, embodiments of this specification also provide a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described... Figure 1 Instructions for an integrated method of hydrogen production, carbon sequestration, and heat extraction for the rock mass shown.

[0159] It should be understood that in the various embodiments of this specification, the sequence number of each process does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this specification.

[0160] It should also be understood that, in the embodiments of this specification, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this specification generally indicates that the preceding and following related objects have an "or" relationship.

[0161] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0162] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0163] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0164] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational tasks to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process.Figure 1 One or more processes and / or boxes Figure 1 The task is a function specified in one or more boxes.

[0165] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for integrating hydrogen production, carbon sequestration, and heat extraction from rock masses, characterized in that, Injection wells and collection wells are arranged in the rock mass; The method includes: Based on the injection well, a mixed fluid is injected into the rock mass to induce serpentinization and carbonatization reactions within the same operating cycle; the mixed fluid includes a circulating working fluid and carbon dioxide; the serpentinization reaction generates hydrogen and releases heat; the carbonatization reaction mineralizes and consolidates carbon dioxide and releases heat. Based on the acquisition well, hydrogen is collected and the exothermic reaction and geothermal energy from the rock mass are recovered.

2. The method according to claim 1, characterized in that, The method of injecting mixed fluids into the rock mass based on the injection well, so that the rock mass undergoes serpentinization and carbonatization reactions within the same operating cycle, includes: Based on the injection well, a mixed fluid is injected into the rock mass so that the circulating working fluid reacts with the magnesium-iron silicate minerals in the rock mass to generate serpentine and magnetite and release hydrogen and heat, and causes carbon dioxide to react with alkaline earth metal ions dissolved from the rock mass to generate carbonate minerals and release heat.

3. The method according to claim 1, characterized in that, The collection wells include hydrogen production wells and thermal recovery wells; The process of collecting hydrogen and recovering the exothermic reaction heat and geothermal energy from the rock mass based on the acquisition well includes: Based on hydrogen-producing wells, recover multiphase fluids including hydrogen; Based on the thermal recovery well, the circulating working fluid is recovered after absorbing the heat released by the reaction and the geothermal energy of the rock mass.

4. The method according to claim 1, characterized in that, Monitoring wells are also arranged in the rock mass; the collection wells include hydrogen production wells and thermal recovery wells; the hydrogen production wells are arranged in the hydrogen accumulation area of ​​the rock mass or in the downstream area of ​​the fluid migration direction; The thermal recovery wells are located in the outer reaction zone, thermal anomaly zone, or thermal breakthrough sensitive zone of the rock mass. The method further includes: Based on the monitoring well, monitoring data of the rock mass reaction zone within the current operating cycle is obtained; the monitoring data includes one or more of the following: pressure field data, chemical field data, temperature field data, resistivity data, seismic data, and tracer response data; Based on the monitoring data, the injection and production parameters of the injection well and the thermal recovery well are adjusted; the injection and production parameters include one or more of the following: injection parameters, acquisition parameters, and injection-production pressure difference between the thermal recovery well and the injection well; the injection parameters include the circulating working fluid parameters and fluid chemical parameters of the mixed fluid injected into the injection well; the acquisition parameters include the heat recovery rate of the thermal recovery well.

5. The method according to claim 4, characterized in that, The step of adjusting the injection and production parameters of the injection well and the thermal recovery well based on the monitoring data includes: Based on the temperature field data and the target reaction temperature ranges corresponding to the serpentinization and carbonation reactions, the heat recovery rate and circulating working fluid parameters are adjusted; the circulating working fluid parameters include one or more of the following: type of circulating working fluid, injection temperature, extraction temperature, circulating flow rate, and pressure.

6. The method according to claim 4, characterized in that, The step of adjusting the injection and production parameters of the injection well and the thermal recovery well based on the monitoring data further includes: Based on the pressure field data, chemical field data, and temperature field data, the dominant serpentinization reaction zone and the dominant carbonatization reaction zone in the rock mass reaction zone are identified. Based on the serpentinization reaction-dominant region and the carbonation reaction-dominant region, the fluid chemical parameters are adjusted; the fluid chemical parameters include one or more of the following: dissolved inorganic carbon concentration, metal ion concentration, pH value, redox potential, and hydrogen concentration.

7. The method according to claim 4, characterized in that, The step of adjusting the injection and production parameters of the injection well and the thermal recovery well based on the monitoring data further includes: Based on the pressure field data, chemical field data, and temperature field data, the dominant serpentinization reaction zone and the dominant carbonatization reaction zone in the rock mass reaction zone are identified. Based on the resistivity data and seismic data, the seepage path of the mixed fluid within the rock mass is identified; Based on the dominant zones of serpentinization and carbonation reactions and the seepage path, the heat recovery rate and circulating working fluid parameters are adjusted to control the reaction intensity of serpentinization and / or carbonation reactions; the circulating working fluid parameters include one or more of the following: type of circulating working fluid, injection temperature, production temperature, circulating flow rate, and pressure.

8. The method according to claim 4, characterized in that, The step of adjusting the injection and production parameters of the injection well and the thermal recovery well based on the monitoring data further includes: Based on the pressure field data, chemical field data, and temperature field data, the dominant serpentinization reaction zone and the dominant carbonatization reaction zone in the rock mass reaction zone are identified. Based on the dominant serpentinization reaction zone, the dominant carbonation reaction zone, and the target reaction temperature ranges corresponding to the serpentinization and carbonation reactions, the heat recovery rate, circulating working fluid parameters, and injection-production pressure difference are adjusted to regulate the spatial distribution of the dominant serpentinization and carbonation reaction zones, as well as the frontal expansion direction and duration of the serpentinization and carbonation reactions.

9. The method according to claim 4, characterized in that, The mixed fluid also includes a chemical activator; the chemical activator is used to promote the dissolution of metal ions in the rock mass that participate in serpentinization and carbonatization reactions; The step of adjusting the injection and production parameters of the injection well and the thermal recovery well based on the monitoring data further includes: Organic ligands with complexing ability less than or equal to a preset complexing ability threshold are used as chemical activators under a preset long-term continuous injection strategy. If one or more of the pressure field data, chemical field data, temperature field data, resistivity data and seismic data meet the preset local activation conditions, an organic ligand with a complexing ability greater than the preset complexing ability threshold will be used as a chemical activator under the preset short-time pulse injection strategy. The preset local activation conditions include: the pressure field data, chemical field data, and temperature field data indicating that the reaction intensity of the rock mass reaction zone is lower than a preset reaction intensity threshold, or the resistivity data and seismic data indicating that the fluid transport efficiency of the seepage path is lower than a preset transport efficiency threshold.

10. The method according to claim 4, characterized in that, The step of adjusting the injection and production parameters of the injection well and the thermal recovery well based on the monitoring data further includes: Based on injection wells, pressure pulses are periodically applied to the rock mass to promote fracture propagation. If one or more of the pressure field data, chemical field data, temperature field data, resistivity data, and seismic data meet the preset local activation conditions, a pressure pulse is applied to the rock mass based on the injection well to promote the propagation of fractures in the rock mass; The preset local activation conditions include: the pressure field data, chemical field data, and temperature field data indicating that the reaction intensity in the reaction zone is lower than a preset reaction intensity threshold, or the resistivity data and seismic data indicating that the fluid transport efficiency of the seepage path is lower than a preset transport efficiency threshold.

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