A method and system for evaluating heat accumulation effect of large water-conducting faults in a rift basin
By constructing a geothermal geological model and solving mathematical models of heat conduction and convection, the problem of accuracy in assessing the heat accumulation effect of large water-conducting faults in rift basins was solved, and a quantitative assessment of the heat accumulation effect and an accurate description of its spatial distribution pattern were achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-02-02
- Publication Date
- 2026-06-09
AI Technical Summary
Existing technologies are insufficient to accurately assess the intensity and spatial distribution of the heat accumulation effect of large water-conducting faults in karst geothermal systems in rift basins, especially in terms of the control effect of deep connectivity on fluid migration and heat transfer.
By acquiring thermal property data from rock samples, a geothermal geological model was constructed, and a geological mathematical model of heat conduction and heat convection was established. The model was then used to perform simulation solutions based on boundary conditions, calculate geothermal gradient and heat flux values, and evaluate the heat accumulation effect of large water-conducting faults.
It enables quantitative assessment of the heat accumulation effect of large-scale water-conducting fractures, improves the accuracy of intensity and spatial distribution patterns, and comprehensively considers water conduction, heat conduction and mechanical response characteristics to simulate fluid flow paths and heat transfer processes.
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Figure CN122174718A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of geothermal resource development technology, and in particular to a method and system for evaluating the heat accumulation effect of large water-conducting fractures in rift basins. Background Technology
[0002] Geothermal energy, as a natural thermal energy source originating from the Earth's interior, is a highly competitive clean and renewable energy source with advantages such as being green and low-carbon, widely distributed, abundant in resources, and safe and stable. It plays an important role in energy structure adjustment and is a key piece of the puzzle for achieving carbon peaking and carbon neutrality. Geothermal resources have enormous potential. Among them, karst geothermal resources in rift basins are gradually becoming the main type of geothermal resources for direct utilization due to their large reserves and ease of reinjection. In karst geothermal systems in rift basins, large water-conducting faults are key channels for fluid flow and heat transfer. The replenishment, runoff, and discharge of groundwater along large water-conducting faults will significantly change the temperature distribution pattern. For example, in cold water infiltration recharge areas, the ground temperature usually shows a negative anomaly, while in hot water upwelling discharge areas, the ground temperature shows a positive anomaly.
[0003] However, existing research on the heat accumulation mechanism of large water-conducting fractures in karst geothermal systems is still limited to the qualitative level. Numerical simulation work has failed to fully depict the entire cycle of groundwater "recharge-runoff-discharge". In particular, it has neglected the control effect of the connectivity of large water-conducting fractures at depth on fluid transport and heat transfer, making it difficult to quantitatively assess the heat accumulation effect of large water-conducting fractures. Consequently, the intensity and spatial distribution of the heat accumulation effect of large water-conducting fractures are inaccurate. Summary of the Invention
[0004] In view of this, it is necessary to provide a method and system for evaluating the heat accumulation effect of large water-conducting fractures in rift basins, so as to solve the technical problem of inaccurate intensity and spatial distribution of the heat accumulation effect of large water-conducting fractures in karst geothermal areas of rift basins.
[0005] To address the aforementioned problems, in a first aspect, the present invention provides a method for evaluating the heat accumulation effect of large water-conducting fractures in rift basins, comprising:
[0006] Thermophysical property data of rock samples from different rock stratigraphic units within a karst geothermal region of a rift basin are obtained, and thermophysical property parameters are obtained based on the thermophysical property data. A geothermal geological model of a karst geothermal region in a rift basin is constructed. Based on the geothermal geological model, a thermal conduction geothermal geological mathematical model and a thermal convection geothermal geological mathematical model considering large water-conducting faults are constructed. Based on the set boundary conditions and thermal property parameters of the geothermal geological model, the thermal conduction geothermal geological mathematical model and the thermal convection geothermal geological mathematical model are simulated and solved respectively to obtain the first geothermal gradient and the second geothermal gradient of the geothermal geological model. The first heat flux value and the second heat flux value of the geothermal geological model are calculated based on the first geothermal gradient and the second geothermal gradient, and the heat accumulation effect of large water-conducting fractures is evaluated based on the first heat flux value and the second heat flux value.
[0007] In one possible implementation, the thermophysical parameters include density, heat capacity, porosity, permeability, thermal conductivity, and heat generation rate.
[0008] In one possible implementation, the mathematical model for geothermal convective geothermal geology is as follows: , , , , , , in, For the density of the fluid, The density of the porous medium, is the specific heat capacity of the fluid. The specific heat capacity of the porous medium, For pressure, Porosity of porous media The permeability coefficient of the porous medium, The thermal conductivity of the fluid, The thermal conductivity of porous media, The rate of radioactive heat generation in rocks, For fluid velocity, For time, For temperature, For dynamic viscosity, For depth, The permeability coefficient of the fault is... This represents the fault width.
[0009] In one possible implementation, the simulation solution of the heat conduction geothermal geological mathematical model and the heat convection geothermal geological mathematical model based on the set boundary conditions and thermal property parameters of the geothermal geological model, respectively, to obtain the first geothermal gradient and the second geothermal gradient of the geothermal geological model, includes: Determine the initial temperature field, velocity field, and pressure field of the geothermal geological model; Based on the initial temperature field, velocity field, and pressure field, the thermal conduction geothermal geological mathematical model and the thermal convection geothermal geological mathematical model are solved respectively to obtain the temperature solution at the current moment. Based on the temperature solution, the viscosity, specific heat capacity, and density of the fluid are calculated, and the thermal property parameters are updated based on the viscosity, specific heat capacity, and density of the fluid. Based on the updated thermal property parameters, the thermal conduction geothermal geological mathematical model and the thermal convection geothermal geological mathematical model are solved iteratively to obtain the first geothermal gradient and the second geothermal gradient of the geothermal geological model.
[0010] In one possible implementation, the boundary conditions include Dirichlet boundary conditions, temperature values, Neumann boundary conditions, and adiabatic boundaries.
[0011] In one possible implementation, the density of the fluid is: , in, The density of the fluid.
[0012] In one possible implementation, the specific heat capacity of the fluid is: , in, is the specific heat capacity of the fluid.
[0013] In one possible implementation, the viscosity of the fluid is: , in, The viscosity is the fluid viscosity.
[0014] In one possible implementation, the assessment of the heat accumulation effect of large-scale water-conducting fractures based on the first heat flux value and the second heat flux value includes: The difference between the first heat flux value and the second heat flux value is calculated to obtain the heat flux difference. The heat accumulation effect of large water-conducting fracture is evaluated based on the heat flux difference.
[0015] Secondly, the present invention also provides a system for evaluating the heat accumulation effect of large water-conducting fractures in rift basins, comprising: The thermal property parameter acquisition module is used to acquire thermal property data of rock samples from different rock stratigraphic units in the karst geothermal area of the rift basin, and to obtain thermal property parameters based on the thermal property data. The simulation module is used to construct a geothermal geological model of a karst geothermal region in a rift basin. Based on the geothermal geological model, a heat conduction geothermal geological mathematical model and a heat convection geothermal geological mathematical model considering large water-conducting faults are constructed. Based on the set boundary conditions and thermal property parameters of the geothermal geological model, the heat conduction geothermal geological mathematical model and the heat convection geothermal geological mathematical model are simulated and solved respectively to obtain the first geothermal gradient and the second geothermal gradient of the geothermal geological model. The heat accumulation effect assessment module is used to calculate the first heat flux value and the second heat flux value of the geothermal geological model based on the first geothermal gradient and the second geothermal gradient, and to assess the heat accumulation effect of large water-conducting fractures based on the first heat flux value and the second heat flux value.
[0016] The beneficial effects of this invention are: obtaining thermal property data of rock samples from different rock stratigraphic units within a karst geothermal region of a rift basin, and obtaining thermal property parameters based on the thermal property data; constructing a geothermal geological model of the karst geothermal region of the rift basin, and based on the geothermal geological model, constructing a thermal conduction geothermal geological mathematical model and a thermal convection geothermal geological mathematical model considering large water-conducting faults; simulating and solving the thermal conduction geothermal geological mathematical model and the thermal convection geothermal geological mathematical model based on the set boundary conditions and thermal property parameters of the geothermal geological model, respectively, to obtain the first geothermal gradient and the second geothermal gradient of the geothermal geological model; calculating the first heat flux value and the second heat flux value of the geothermal geological model based on the first geothermal gradient and the second geothermal gradient, and then calculating the first heat flux value and the second heat flux value of the geothermal geological model based on the first heat flux value and the second heat flux value. The heat flux value is used to assess the heat accumulation effect of large water-conducting fractures. Through simulation by a geothermal geological mathematical model of thermal convection, the water-conducting, heat-conducting, and mechanical response characteristics of the fracture zone can be comprehensively considered. It can accurately simulate the flow path and heat transfer process of fluids in large water-conducting fractures, effectively solving the problem of neglecting the control of fluid migration and heat transfer by the deep connectivity of large water-conducting fractures. By comparing the thermal conduction geothermal geological mathematical model and the thermal convection geothermal geological mathematical model, the difference between the first and second heat flux values is used to characterize the intensity and distribution characteristics of the heat accumulation effect of large water-conducting fractures. This enables a quantitative assessment of the spatial distribution and intensity of the heat accumulation effect of large water-conducting fractures, improving the accuracy of the intensity and spatial distribution law of the heat accumulation effect of large water-conducting fractures in karst geothermal areas of rift basins. Attached Figure Description
[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0018] Figure 1A flowchart of an embodiment of the method for evaluating the heat accumulation effect of large water-conducting fractures in rift basins provided by the present invention; Figure 2 A schematic diagram of the geothermal geological model for the method of evaluating the heat accumulation effect of large water-conducting faults in rift basins provided by the present invention. Figure 3 A schematic diagram of the boundary conditions of the geothermal geological model for the method of evaluating the heat accumulation effect of large water-conducting faults in rift basins provided by the present invention. Figure 4a A schematic diagram of the temperature field of the temperature distribution pattern of the thermal conductivity geothermal geological mathematical model for the evaluation method of the heat accumulation effect of large water-conducting faults in rift basins provided by the present invention. Figure 4b A schematic diagram of the temperature field of the temperature distribution pattern of the thermal convection geothermal geological mathematical model for the evaluation method of the heat accumulation effect of large water-conducting faults in rift basins provided by the present invention. Figure 4c A schematic diagram of the head field distribution of the thermal convection geothermal geological mathematical model for the evaluation method of the heat accumulation effect of large water-conducting faults in rift basins provided by the present invention. Figure 5 A schematic diagram of the heat flux results provided by the method for evaluating the heat accumulation effect of large water-conducting fractures in rift basins according to the present invention. Figure 6 This is a schematic diagram of an embodiment of the thermal accumulation effect assessment system for large-scale water-conducting fractures in rift basins provided by the present invention. Detailed Implementation
[0019] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.
[0020] In this document, the term "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.
[0021] A specific embodiment of the present invention discloses a method for evaluating the heat accumulation effect of large water-conducting faults in rift basins, such as... Figure 1 As shown, the method for assessing the heat accumulation effect of large water-conducting faults in rift basins includes: S101. Obtain thermal property data of rock samples from different rock stratigraphic units within the karst geothermal area of the rift basin, and obtain thermal property parameters based on the thermal property data; S102. Construct a geothermal geological model of a karst geothermal region in a rift basin. Based on the geothermal geological model, construct a thermal conduction geothermal geological mathematical model and a thermal convection geothermal geological mathematical model considering large water-conducting faults. Based on the set boundary conditions and thermal property parameters of the geothermal geological model, simulate and solve the thermal conduction geothermal geological mathematical model and the thermal convection geothermal geological mathematical model respectively to obtain the first geothermal gradient and the second geothermal gradient of the geothermal geological model. It should be noted that the simulation solutions of the thermal conduction geothermal geological mathematical model and the thermal convection geothermal geological mathematical model have improved the accuracy of the intensity and spatial distribution of the heat accumulation effect of large water-conducting fractures in karst geothermal basins.
[0022] S103. Calculate the first heat flux value and the second heat flux value of the geothermal geological model based on the first geothermal gradient and the second geothermal gradient, and evaluate the heat accumulation effect of large water-conducting fractures based on the first heat flux value and the second heat flux value.
[0023] In some embodiments, in step S101, thermal property data of rock samples from different lithofacies units within a karst geothermal area of a rift basin are acquired. Thermal property parameters are obtained based on this data. A rock thermal property library is constructed based on the measured thermal property data of rock samples from the study area (karst geothermal area of a rift basin). Thermal property parameters for different lithofacies units are obtained through the thermal property data, including density, heat capacity, porosity, permeability, thermal conductivity, and heat generation rate, providing fundamental parameters for establishing a geothermal geological model. In some embodiments, in step S102, a geothermal geological model of a karst geothermal region in a rift basin is constructed. Based on geophysical and borehole data, rock stratigraphic units are divided and a geological model is established. This model can be a three-dimensional or two-dimensional model. After setting corresponding rock thermal property parameters for different stratigraphic units, a geothermal geological model of the karst geothermal region in a rift basin is constructed. For a schematic diagram of the geothermal geological model, please refer to [link / reference needed]. Figure 2 ,like Figure 2 As shown, the rock stratigraphic units in the geothermal geological model include the Archean-Lower Proterozoic (Ar~Pt1) basement, the Middle-Upper Proterozoic (Pt2-3) carbonate strata, and the Lower Paleozoic Cambrian-Ordovician (…). The stratigraphic units include carbonate rocks, Upper Paleozoic Carboniferous-Permian (C~P) sandstone and mudstone (locally developed), Mesozoic (Mz) sandstone and mudstone (locally developed), Paleogene (E) sandstone and mudstone, Neogene (N) sandstone and mudstone, and Quaternary (Q) clay layers. The tops of the Middle-Upper Proterozoic, Cambrian, and Ordovician carbonate rocks are karst geothermal reservoirs. For the thermal properties of these lithofacies units, please refer to Table 1. Table 1
[0024] As shown in Table 1, corresponding rock thermal property parameters, including thermal conductivity, were set for different rock stratigraphic units. Radioactive heat generation rate Specific heat capacity ,density Porosity and penetration rate ; Based on geothermal geological models, a geothermal geological mathematical model considering heat conduction and heat convection is constructed. In the aquifer, the rock strata are considered as porous media, and their heat transfer process is described by the energy conservation equation (heat transfer in porous media), i.e., a geothermal geological mathematical model considering only heat conduction. The groundwater flow process is described using the fluid continuity equation and Darcy's law, i.e., a geothermal geological mathematical model superimposed with forced convection and free convection under the heat conduction mechanism. The geothermal geological mathematical model for heat convection is as follows: , , , , , , in, For the density of the fluid, The density of the porous medium, is the specific heat capacity of the fluid. The specific heat capacity of the porous medium, For pressure, Porosity of porous media The permeability coefficient of the porous medium, The thermal conductivity of the fluid, The thermal conductivity of porous media, The rate of radioactive heat generation in rocks, For fluid velocity, For time, For temperature, For dynamic viscosity, For depth, The permeability coefficient of the fault is... The permeability coefficient varies with fluid viscosity and density, representing the fault width. With penetration rate The relationship is: , Its heat conduction geothermal geological mathematical model is as follows: , , Based on the established boundary conditions and thermophysical parameters of the geothermal geological model, simulations were performed on both the heat conduction and convection geothermal geological mathematical models to obtain the first and second geothermal gradients and determine the initial temperature, velocity, and pressure fields. Based on these initial temperature, velocity, and pressure fields, the heat conduction and convection geothermal geological mathematical models were solved to obtain the current temperature solution. The viscosity, specific heat capacity, and density of the fluid were then calculated from these temperature solutions. The thermal property parameters are updated. Based on the updated thermal property parameters, the thermal conduction geothermal geological mathematical model and the thermal convection geothermal geological mathematical model are iteratively solved to obtain the first and second geothermal gradients of the geothermal geological model. The first geothermal gradient is obtained through simulation of the thermal conduction geothermal geological mathematical model, and the second geothermal gradient is obtained through simulation of the thermal convection geothermal geological mathematical model. The boundary conditions of the geothermal geological model include Dirichlet boundary conditions, temperature values, Neumann boundary conditions, and adiabatic boundaries. For a schematic diagram of the boundary conditions of the geothermal geological model, please refer to [link / reference needed]. Figure 3 ,like Figure 3 As shown, the model surface temperature is generally the regional annual average temperature and is an open boundary, set as follows: The model's bottom boundary is given a constant heat flux value, with adiabatic boundaries on both sides and no lateral water flow. The top boundary of the model uses surface elevation to approximate the actual groundwater surface slope. The top boundary of the geothermal geological model is set as a Dirichlet boundary condition, with the temperature value being the region's annual average air temperature. The bottom boundary of the model uses a Neumann boundary condition, i.e., a constant heat flux value is given, which is calculated based on the surface heat flux value of the study area using the back-stripping method. Both sides of the model are adiabatic boundaries. For flow boundary conditions, the heat conduction geothermal geological mathematical model only considers heat conduction and does not require setting flow conditions. In the heat convection geothermal geological mathematical model, the sides and bottom are non-flowing boundaries. The shape of the groundwater surface at the top of the model is controlled by the terrain, and the surface elevation is used to approximate the actual groundwater surface slope. During simulation, The geothermal geological model is meshed by dividing the continuous physical region into discrete finite element meshes. These meshes divide the model into many smaller domains, called elements. Then, the geothermal geological mathematical models of heat conduction and heat convection are solved on these elements. The required governing equations are approximated by a set of polynomial functions defined on each element. As the mesh is refined, these elements become smaller, thus making the solution increasingly closer to the true solution. COMSOL's mesh generation tool divides the two-dimensional space of the geothermal geological model into many small, interconnected, non-overlapping finite element (element) meshes using free triangular meshes with a resolution ranging from 0.26 to 87.1. The model was meshed using the Delaunay method (where four points cannot be concyclic, and two adjacent triangles form the diagonal of a convex quadrilateral; after exchanging triangles, the smallest of the six interior angles no longer increases), resulting in 702,929 domain elements and 19,024 boundary elements. Furthermore, the fault was reduced in dimension to one-dimensional line elements, equivalent to fractures with extremely large apertures. This avoids extensive fine meshing in the fracture region, reducing computational load and improving efficiency. Next, the local differential equations on each element were converted into algebraic equations through numerical integration. This was done by selecting finite polynomial functions, superimposing them, and requiring the weighted integral of the results within the solution domain and on the boundary to satisfy the original equations. This yielded a set of easily solvable algebraic equations. These equations are then combined into a large sparse matrix system. Since physical properties change with temperature, the matrix elements need to be dynamically updated based on the current temperature solution in each iteration. The initial temperature field, velocity field, and pressure field are determined as the starting point for iteration. Starting from these initial fields, for each iteration, the viscosity, heat capacity, and density of the fluid are calculated based on the current temperature solution. During the calculation, the coupling relationship between the temperature field and the seepage field is mainly realized through the changes in groundwater-related parameters (such as water density, dynamic viscosity, and specific heat capacity). That is, when there is a temperature difference, the physical parameters of groundwater no longer remain constant but change as a function of temperature. The density of the fluid, i.e., the groundwater density, is a function of temperature change. , in, The density of the fluid; The heat capacity of the fluid, i.e., the specific heat capacity of groundwater, varies with temperature as follows: , in, Specific heat capacity of the fluid; The functional relationship between groundwater thermal conductivity and temperature is as follows: , in, The thermal conductivity of the fluid; The viscosity of the fluid is: , in, The viscosity of the fluid; The fluid's physical properties are updated using viscosity, heat capacity, and density. Based on these updated properties, the discretized equations for fluid flow and heat transfer are recalculated and reassembled. Next, the updated equations are solved. Once new velocity, pressure, and temperature fields are obtained, they are fed back into the model to update the field variables across the entire domain. This process is repeated continuously in nonlinear iterations until all relevant physical quantities reach the convergence criterion. The entire simulation period is divided into a series of small time steps, and the solution steps are repeated at each time step until the solution converges. After completing the calculation for one time step, the solution is used as the initial value for the next time step. Finally, the temperature distribution patterns of the geothermal geological model simulated by the thermal conduction and thermal convection models are obtained. Based on these temperature distribution patterns, the first and second geothermal gradients of the geothermal geological model are derived. For a schematic diagram of the temperature field of the thermal conduction geothermal geological mathematical model, please refer to [link / reference needed]. Figure 4a Please refer to the temperature field diagram of the temperature distribution pattern in the thermal convection geothermal geological mathematical model. Figure 4b ,like Figure 4a and Figure 4b As shown, the fluid from large water-conducting faults significantly affects the temperature distribution of rock stratigraphic units. For a schematic diagram of the head field distribution in the geothermal geological mathematical model of its thermal convection, please refer to [link / reference needed]. Figure 4c ,like Figure 4c The direction of the arrow indicates the fluid flow direction of a large water-conducting fracture.
[0025] In some embodiments, in step S103, the first heat flux value and the second heat flux value of the geothermal geological model are calculated based on the first geothermal gradient and the second geothermal gradient. The geothermal gradient of the model can be obtained according to the temperature distribution pattern simulated numerically. Multiplying the geothermal gradient by the thermal conductivity yields the heat flux value of the model surface. For a schematic diagram of the heat flux results, please refer to [link to schematic diagram]. Figure 5 ,like Figure 5 As shown, the simulated heat flux M1 corresponds to the heat flux obtained after simulation by the heat conduction geothermal geological mathematical model, i.e., the first heat flux value. The simulated heat flux M2 corresponds to the heat flux obtained after simulation by the heat convection geothermal geological mathematical model, i.e., the second heat flux value. The heat accumulation effect of large water-conducting faults is evaluated based on the first and second heat flux values. The difference between the first and second heat flux values is calculated to obtain the heat flux difference. The heat accumulation effect of large water-conducting faults is evaluated based on this heat flux difference. The surface heat flux difference calculated by the heat convection geothermal geological mathematical model (M2) and the heat conduction (porous medium heat transfer) geothermal geological mathematical model (M1) represents the groundwater convection heat accumulation effect of large water-conducting faults. For the heat flux results of the Rongdong Uplift and the Niutuo Town Uplift as examples, please refer to Table 2. Table 2
[0026] As shown in Table 2, the contribution share of thermal convection is the difference between the surface heat flux of M2 and the surface heat flux of M1. The contribution share of thermal convection represents the heat accumulation effect of groundwater convection in large faults. The heat accumulation effect of groundwater convection in large faults can be evaluated by the contribution share of thermal convection.
[0027] In summary, the method for evaluating the heat accumulation effect of large water-conducting faults in rift basins provided by this invention obtains thermal property data of rock samples from different rock stratigraphic units within the karst geothermal region of the rift basin, and obtains thermal property parameters based on the thermal property data; constructs a geothermal geological model of the karst geothermal region of the rift basin, and based on the geothermal geological model, constructs a thermal conduction geothermal geological mathematical model and a thermal convection geothermal geological mathematical model considering large water-conducting faults; simulates and solves the thermal conduction geothermal geological mathematical model and the thermal convection geothermal geological mathematical model respectively based on the set boundary conditions and thermal property parameters of the geothermal geological model, and obtains the first geothermal gradient and the second geothermal gradient of the geothermal geological model; calculates the first heat flux value and the second heat flux value of the geothermal geological model based on the first geothermal gradient and the second geothermal gradient, and evaluates the heat accumulation effect of large water-conducting faults based on the first heat flux value and the second heat flux value, thereby improving the accuracy of the intensity and spatial distribution law of the heat accumulation effect of large water-conducting faults in karst geothermal regions of rift basins.
[0028] To better implement the method for evaluating the thermal accumulation effect of large water-conducting fractures in rift basins as described in this invention, based on the method for evaluating the thermal accumulation effect of large water-conducting fractures in rift basins, the corresponding method is as follows: Figure 6 As shown, this embodiment of the invention also provides a system for assessing the thermal accumulation effect of large water-conducting faults in rift basins. The system 600 for assessing the thermal accumulation effect of large water-conducting faults in rift basins includes: The thermal property parameter acquisition module 601 is used to acquire thermal property data of rock samples from different rock stratigraphic units in the karst geothermal area of the rift basin, and to obtain thermal property parameters based on the thermal property data. Simulation module 602 is used to construct a geothermal geological model of a karst geothermal region in a rift basin. Based on the geothermal geological model, a heat conduction geothermal geological mathematical model and a heat convection geothermal geological mathematical model considering large water-conducting faults are constructed. Based on the set boundary conditions and thermal property parameters of the geothermal geological model, the heat conduction geothermal geological mathematical model and the heat convection geothermal geological mathematical model are simulated and solved respectively to obtain the first geothermal gradient and the second geothermal gradient of the geothermal geological model. The heat accumulation effect assessment module 603 is used to calculate the first heat flux value and the second heat flux value of the geothermal geological model based on the first geothermal gradient and the second geothermal gradient, and to assess the heat accumulation effect of large water-conducting fractures based on the first heat flux value and the second heat flux value.
[0029] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.
Claims
1. A method for evaluating the heat accumulation effect of large water-conducting faults in rift basins, characterized in that, include: Thermophysical property data of rock samples from different rock stratigraphic units within a karst geothermal region of a rift basin are obtained, and thermophysical property parameters are obtained based on the thermophysical property data. A geothermal geological model of a karst geothermal region in a rift basin is constructed. Based on the geothermal geological model, a thermal conduction geothermal geological mathematical model and a thermal convection geothermal geological mathematical model considering large water-conducting faults are constructed. Based on the set boundary conditions and thermal property parameters of the geothermal geological model, the thermal conduction geothermal geological mathematical model and the thermal convection geothermal geological mathematical model are simulated and solved respectively to obtain the first geothermal gradient and the second geothermal gradient of the geothermal geological model. The first heat flux value and the second heat flux value of the geothermal geological model are calculated based on the first geothermal gradient and the second geothermal gradient, and the heat accumulation effect of large water-conducting fractures is evaluated based on the first heat flux value and the second heat flux value.
2. The method for evaluating the heat accumulation effect of large water-conducting faults in rift basins according to claim 1, characterized in that, The thermophysical parameters include density, heat capacity, porosity, permeability, thermal conductivity, and heat generation rate.
3. The method for evaluating the heat accumulation effect of large water-conducting faults in rift basins according to claim 2, characterized in that, The mathematical model for geothermal convective geothermal geology is as follows: ， ， ， ， ， ， in, For the density of the fluid, The density of the porous medium, is the specific heat capacity of the fluid. The specific heat capacity of the porous medium, For pressure, Porosity of porous media The permeability coefficient of the porous medium, The thermal conductivity of the fluid, The thermal conductivity of porous media, The rate of radioactive heat generation in rocks, For fluid velocity, For time, For temperature, For dynamic viscosity, For depth, The permeability coefficient of the fault is... This represents the fault width.
4. The method for evaluating the heat accumulation effect of large water-conducting faults in rift basins according to claim 3, characterized in that, The geothermal geological model is simulated and solved using the boundary conditions and thermal property parameters of the established geothermal geological model, respectively, to obtain the first geothermal gradient and the second geothermal gradient of the geothermal geological model, including: Determine the initial temperature field, velocity field, and pressure field of the geothermal geological model; Based on the initial temperature field, velocity field, and pressure field, the thermal conduction geothermal geological mathematical model and the thermal convection geothermal geological mathematical model are solved respectively to obtain the temperature solution at the current moment. Based on the temperature solution, the viscosity, specific heat capacity, and density of the fluid are calculated, and the thermal property parameters are updated based on the viscosity, specific heat capacity, and density of the fluid. Based on the updated thermal property parameters, the thermal conduction geothermal geological mathematical model and the thermal convection geothermal geological mathematical model are solved iteratively to obtain the first geothermal gradient and the second geothermal gradient of the geothermal geological model.
5. The method for evaluating the heat accumulation effect of large water-conducting faults in rift basins according to claim 4, characterized in that, The boundary conditions include Dirichlet boundary conditions, temperature values, Neumann boundary conditions, and adiabatic boundaries.
6. The method for evaluating the heat accumulation effect of large water-conducting faults in rift basins according to claim 4, characterized in that, The density of the fluid is: ， in, The density of the fluid.
7. The method for evaluating the heat accumulation effect of large water-conducting faults in rift basins according to claim 4, characterized in that, The specific heat capacity of the fluid is: ， in, is the specific heat capacity of the fluid.
8. The method for evaluating the heat accumulation effect of large water-conducting faults in rift basins according to claim 4, characterized in that, The viscosity of the fluid is: ， in, The viscosity is the fluid viscosity.
9. The method for evaluating the heat accumulation effect of large water-conducting faults in rift basins according to claim 4, characterized in that, The assessment of the heat accumulation effect of large-scale water-conducting fractures based on the first heat flux value and the second heat flux value includes: The difference between the first heat flux value and the second heat flux value is calculated to obtain the heat flux difference. The heat accumulation effect of large water-conducting fracture is evaluated based on the heat flux difference.
10. A system for evaluating the heat accumulation effect of large water-conducting faults in rift basins, characterized in that, include: The thermal property parameter acquisition module is used to acquire thermal property data of rock samples from different rock stratigraphic units in the karst geothermal area of the rift basin, and to obtain thermal property parameters based on the thermal property data. The simulation module is used to construct a geothermal geological model of a karst geothermal region in a rift basin. Based on the geothermal geological model, a heat conduction geothermal geological mathematical model and a heat convection geothermal geological mathematical model considering large water-conducting faults are constructed. Based on the set boundary conditions and thermal property parameters of the geothermal geological model, the heat conduction geothermal geological mathematical model and the heat convection geothermal geological mathematical model are simulated and solved respectively to obtain the first geothermal gradient and the second geothermal gradient of the geothermal geological model. The heat accumulation effect assessment module is used to calculate the first heat flux value and the second heat flux value of the geothermal geological model based on the first geothermal gradient and the second geothermal gradient, and to assess the heat accumulation effect of large water-conducting fractures based on the first heat flux value and the second heat flux value.