Heat transfer parameter inversion method, apparatus, computer device and storage medium

Abstract

The present invention relates to the technical field of geothermal resource assessment. Disclosed are a heat transfer parameter inversion method, an apparatus, a computer device and a storage medium. The method comprises: on the basis of drilling data of a target area and hydrogeological data of the target data, carrying out a three-stage single-well injection-extraction test, so as to determine influencing parameters of a wellbore thermal mixing process; on the basis of the influencing parameters of the wellbore thermal mixing process, constructing a single-well injection-extraction test mathematical model considering the wellbore thermal mixing process; solving the single-well injection-extraction test mathematical model considering the wellbore thermal mixing process, so as to generate a three-stage single-well injection-extraction test analytical solution; and constructing an optimization objective function on the basis of the three-stage single-well injection-extraction test analytical solution, and using the optimization objective function for parameter inversion so as to generate heat transfer parameter values of a target fractured aquifer, the heat transfer parameter values of the target fractured aquifer being used for assessing geothermal resources. The present invention improves the inversion precision and the calculation efficiency of geothermal transfer parameters.

Description

A heat transfer parameter inversion method, device, computer equipment and storage medium Technical Field

[0001] The present invention relates to the technical field of geothermal resource assessment, and in particular to a heat transfer parameter inversion method, device, computer equipment and storage medium. Background Art

[0002] With rapid economic development, fossil energy consumption is increasing, and environmental issues are becoming increasingly prominent. There is an urgent need to find alternative energy sources to alleviate the dual pressures of energy and the environment, especially with the advent of the "dual carbon" goals. Geothermal energy, primarily derived from heat generated within the Earth, boasts large reserves, minimal impact from weather changes, excellent stability, wide distribution, and its development and utilization does not directly emit carbon dioxide. Furthermore, geothermal energy is a renewable, clean energy source with diverse applications. It can be used for heating and power generation, but also as a valuable resource for medical thermal mineral water. It possesses significant market potential and broad development prospects. The development and utilization of geothermal resources has already and will undoubtedly secure a place in the global new energy landscape. Fractured aquifers are the primary reservoir for deep geothermal heat. Heat transfer parameters are essential for assessing the potential and efficiency of geothermal resource development. Therefore, the accuracy of these inverse-derived parameters is crucial.

[0003] However, the accuracy of the relevant heat transfer parameter inversion methods is low, which in turn reduces the mining potential and development and utilization efficiency of geothermal resources.

[0004] Summary of the Invention

[0005] In view of this, the present invention provides a heat transfer parameter inversion method, apparatus, computer equipment and storage medium to solve the problem that the relevant heat transfer parameter inversion methods have low accuracy, thereby reducing the mining potential and development and utilization efficiency of geothermal resources.

[0006] In a first aspect, the present invention provides a heat transfer parameter inversion method, the method comprising:

[0007] Obtain borehole data and hydrogeological data for the target area, conduct a three-stage single-well injection and pumping test based on the borehole data and hydrogeological data for the target area, and determine the influencing parameters of the wellbore thermal mixing process;

[0008] Based on the influencing parameters of the wellbore thermal mixing process, a mathematical model for single-well injection and pumping test considering the wellbore thermal mixing process is constructed;

[0009] The mathematical model of the single-well injection and pumping test considering the wellbore thermal mixing process is solved to generate the analytical solution of the three-stage single-well injection and pumping test;

[0010] An optimization objective function is constructed based on the analytical solution of a three-stage single-well injection and pumping test. Parameter inversion is performed using the optimization objective function to generate heat transfer parameter values ​​for the target fractured aquifer. These heat transfer parameter values ​​are used to evaluate geothermal resources.

[0011] This embodiment provides a heat transfer parameter inversion method. This method takes into account the wellbore thermal mixing process by constructing a mathematical model for a single-well injection and pumping test. The mathematical model for the single-well injection and pumping test taking into account the wellbore thermal mixing process is solved to generate an analytical solution for the three-stage single-well injection and pumping test. An optimization objective function is then constructed based on the analytical solution for the three-stage single-well injection and pumping test. This method can be used to invert and set key parameters in a heat transfer model in a fractured aquifer. It can solve the problem of parameter identification in the numerical simulation of heat transfer in fractured aquifers, improve the accuracy and computational efficiency of parameter inversion, and provide technical support for the spatial distribution assessment of geothermal resources and the efficient development of geothermal resources.

[0012] In an optional embodiment, a three-stage single-well injection and pumping test is conducted based on the target area drilling data and the target area hydrogeological data to determine the influencing parameters of the wellbore thermal mixing process, including:

[0013] Determine target fractured aquifers and geothermal injection wells based on target area drilling data and target area hydrogeological data;

[0014] Measure the target fractured aquifer and geothermal injection well to determine the bedrock thickness and wellbore radius;

[0015] obtaining the lithology of the target fractured aquifer and determining a range of geothermal heat transfer parameters based on the lithology of the target fractured aquifer;

[0016] The temperature of the target fractured aquifer is obtained, and a three-stage single-well injection and pumping test is carried out based on the temperature of the target fractured aquifer to determine the injection flow rate, pumping flow rate, liquid volume in the geothermal injection well, temperature in the geothermal injection well and temperature of the injected water body; among them, the three-stage single-well injection and pumping test includes single-well injection and pumping tests in the injection stage, the rest stage and the pumping stage.

[0017] This embodiment provides a heat transfer parameter inversion method that calculates relevant data of the target fractured aquifer and geothermal injection well to determine the influencing parameters of the wellbore thermal mixing process. This lays the foundation for the subsequent mathematical model of single-well injection and pumping tests that consider the wellbore thermal mixing process. The range of geothermal transfer parameters also lays the foundation for the accuracy judgment of the heat transfer parameter values ​​of the target fractured aquifer generated by subsequent inversion.

[0018] In an optional embodiment, the geothermal heat transfer parameters in the range of geothermal heat transfer parameters include:

[0019] Volumetric specific heat capacity of bedrock medium, thermal conductivity coefficient of bedrock medium, volumetric specific heat capacity of target fractured aquifer, porosity of target fractured aquifer, thermal diffusion of target fractured aquifer, width of target fractured aquifer, thermal conductivity coefficient of target fractured aquifer, and volumetric specific heat capacity of water.

[0020] The present embodiment provides a heat transfer parameter inversion method that solves the problem of parameter identification during heat transfer numerical simulation by inverting key heat transfer parameters, such as the thermal expansion coefficient and the thermal diffusion coefficient.

[0021] In an optional embodiment, a mathematical model for a single-well injection and pumping test considering the wellbore thermal mixing process is constructed based on the influencing parameters of the wellbore thermal mixing process, including:

[0022] Based on the influencing parameters of the wellbore thermal mixing process, the injection stage mixing effect model, the rest stage mixing effect model and the extraction stage mixing effect model are constructed respectively.

[0023] Based on the influencing parameters of the wellbore thermal mixing process, the control equations are constructed; wherein the control equations include the thermal transfer kinetic equations of the fracture medium and the thermal transfer kinetic equations of the bedrock medium;

[0024] Determine the initial and boundary conditions based on the influencing parameters of the wellbore thermal mixing process;

[0025] Determine the effective thermal diffusivity based on the influencing parameters of the wellbore thermal mixing process;

[0026] A mathematical model of single-well injection and extraction test considering the wellbore thermal mixing process is constructed based on the heat transfer kinetic equation, initial conditions, boundary conditions, effective thermal diffusivity, injection stage mixing effect model, rest stage mixing effect model and extraction stage mixing effect model.

[0027] This embodiment provides a heat transfer parameter inversion method. Existing analytical solutions for three-stage single-well injection and pumping geothermal transfer all assume a linear relationship between geothermal diffusion and flow velocity, an assumption that often violates actual physical laws. This embodiment considers the nonlinear relationship between heat diffusion and flow velocity in the construction of a mathematical model for a single-well injection and pumping test that takes into account the wellbore thermal mixing process, thereby improving the simulation capability of the heat transfer process in fractured aquifers and the accuracy of heat transfer parameter inversion.

[0028] In an optional embodiment, based on the influencing parameters of the wellbore thermal mixing process, a mixed effect model for the injection phase, a mixed effect model for the rest phase, and a mixed effect model for the extraction phase are constructed respectively, including:

[0029] A mixed effect model for the injection phase was constructed based on the volumetric specific heat capacity of water, the liquid volume in the geothermal injection well during the injection phase, the temperature in the geothermal injection well, the injection flow rate, and the temperature of the injected water.

[0030] A rest phase mixed-effect model is constructed based on the temperature in the geothermal injection well and the temperature of the target fractured aquifer;

[0031] A mixed-effect model for the extraction phase was constructed based on the pumping flow rate, volumetric specific heat capacity of water, liquid volume in the geothermal injection well during the extraction phase, temperature in the geothermal injection well, width of the target fractured aquifer, bedrock thickness, thermal conductivity of the target fractured aquifer, and temperature of the target fractured aquifer.

[0032] This embodiment provides a heat transfer parameter inversion method that constructs a mixed-effect model for the injection phase, a mixed-effect model for the rest phase, and a mixed-effect model for the extraction phase. A corresponding model is constructed for each phase of a single-well injection and extraction test, thereby improving the simulation capability of the heat transfer process in the target fractured aquifer.

[0033] In an optional embodiment, a control equation is constructed based on the influencing parameters of the wellbore thermal mixing process, including:

[0034] Obtaining the temperature of the bedrock medium and the flow velocity of the target fractured aquifer, and constructing a fractured medium heat transfer kinetic equation based on the volumetric specific heat capacity of the target fractured aquifer, the temperature of the target fractured aquifer, the thermal conductivity coefficient of the target fractured aquifer, the thermal diffusivity of the target fractured aquifer, the volumetric specific heat capacity of water, the porosity of the target fractured aquifer, the thermal conductivity coefficient of the bedrock medium, the width of the target fractured aquifer, the temperature of the bedrock medium, and the flow velocity of the target fractured aquifer;

[0035] The bedrock medium heat transfer kinetic equation is constructed based on the volume specific heat capacity of the bedrock medium, the bedrock medium temperature, and the bedrock medium thermal conductivity coefficient.

[0036] The present embodiment provides a heat transfer parameter inversion method, which improves the simulation capability of the heat transfer process in the target fractured aquifer by constructing the heat transfer kinetic equation of fractured media and the heat transfer kinetic equation of bedrock media.

[0037] In an optional embodiment, determining the initial conditions and boundary conditions based on the influencing parameters of the wellbore thermal mixing process includes:

[0038] obtaining initial temperatures in the fracture and bedrock media, and constructing initial conditions based on the temperature of the target fracture aquifer, the temperature of the bedrock media, and the initial temperatures in the fracture and bedrock media;

[0039] Boundary conditions are constructed based on the temperature of the target fractured aquifer, the temperature of the bedrock medium, the temperature within the geothermal injection well, and the initial temperatures in the fracture and bedrock media.

[0040] The heat transfer parameter inversion method provided in this embodiment improves the simulation capability of the heat transfer process in the target fractured aquifer by constructing initial conditions and boundary conditions, thereby improving the accuracy of subsequent heat transfer parameter inversion.

[0041] In an optional embodiment, determining the effective thermal diffusion coefficient based on the influencing parameters of the wellbore thermal mixing process includes:

[0042] The effective thermal diffusivity is determined based on the thermal conductivity of the target fractured aquifer, the volumetric specific heat capacity of the target fractured aquifer, the thermal diffusivity of the target fractured aquifer, the volumetric specific heat capacity of water, and the flow velocity of the target fractured aquifer.

[0043] In an optional embodiment, an optimization objective function is constructed based on the analytical solution of the three-stage single-well injection and pumping test, and parameter inversion is performed using the optimization objective function to generate heat transfer parameter values ​​for the target fractured aquifer, including:

[0044] Based on the analytical solution of the three-stage single-well injection and pumping test, an optimization objective function is constructed with the goal of minimizing the fitting value of the three-stage single-well injection and pumping test;

[0045] The optimization objective function is solved to generate the heat transfer parameter values ​​of the target fractured aquifer.

[0046] This embodiment provides a heat transfer parameter inversion method that combines an optimization objective function to invert key geothermal parameters, greatly improving the efficiency of parameter inversion. Moreover, compared with existing methods, it is more convenient for engineering promotion and application, providing technical support for the evaluation of the mining potential and development and utilization efficiency of geothermal resources.

[0047] In an optional embodiment, based on the analytical solution of the three-stage single-well injection and pumping test, an optimization objective function is constructed with the goal of minimizing the fitting value of the three-stage single-well injection and pumping test, including:

[0048] Determine the simulated values ​​of sampling points based on the analytical solution of the three-stage single-well injection and pumping test;

[0049] Obtain the observed values ​​of the sampling points, and determine the mean square error of the three-stage single-well injection and pumping test based on the simulated values ​​and the observed values ​​of the sampling points;

[0050] The weighted coefficient of the three-stage single-well injection and pumping test is obtained, and the optimization objective function is constructed based on the mean square error value of the three-stage single-well injection and pumping test and the weighted coefficient of the three-stage single-well injection and pumping test.

[0051] This embodiment provides a heat transfer parameter inversion method, which constructs an optimization objective function with the goal of minimizing the fitting value of a three-stage single-well injection and pumping test, thereby improving the efficiency and accuracy of parameter inversion.

[0052] In an optional embodiment, an optimization objective function is constructed based on the mean square error value of the three-stage single-well injection and pumping test and the weighting coefficient of the three-stage single-well injection and pumping test. The expression of the optimization objective function is as follows:

[0053] In the above formula, F represents the optimization objective function, μ i represents the weighting coefficient of the i-th stage, Δf i represents the mean square error value of the i-th stage, and u represents the number of stages in the single-well injection and pumping test.

[0054] In an optional embodiment, the method further includes:

[0055] The heat transfer parameter value of the target fractured aquifer is compared with the range of the geothermal transfer parameter, and when the heat transfer parameter value of the target fractured aquifer meets the range of the geothermal transfer parameter, the heat transfer parameter value of the target fractured aquifer is output.

[0056] In a second aspect, the present invention provides a heat transfer parameter inversion device, the device comprising:

[0057] An acquisition module is used to obtain the target area drilling data and the target area hydrogeological data, and to carry out a three-stage single-well injection and pumping test based on the target area drilling data and the target area hydrogeological data to determine the influencing parameters of the wellbore thermal mixing process;

[0058] A construction module is used to construct a mathematical model for a single-well injection and pumping test considering the wellbore thermal mixing process based on the influencing parameters of the wellbore thermal mixing process;

[0059] The solution module is used to solve the mathematical model of the single-well injection and pumping test considering the wellbore thermal mixing process and generate the analytical solution of the three-stage single-well injection and pumping test;

[0060] The inversion module is used to construct an optimization objective function based on the analytical solution of the three-stage single-well injection and pumping test, and use the optimization objective function to perform parameter inversion to generate the heat transfer parameter values ​​of the target fractured aquifer; among them, the heat transfer parameter values ​​of the target fractured aquifer are used to evaluate geothermal resources.

[0061] In a third aspect, the present invention provides a computer device comprising: a memory and a processor, the memory and the processor being communicatively connected to each other, the memory storing computer instructions, and the processor executing the computer instructions to thereby execute a heat transfer parameter inversion method according to the first aspect or any corresponding embodiment thereof.

[0062] In a fourth aspect, the present invention provides a computer-readable storage medium having computer instructions stored thereon, the computer instructions being used to enable a computer to execute a heat transfer parameter inversion method according to the first aspect or any corresponding embodiment thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0064] FIG1 is a schematic flow chart of a heat transfer parameter inversion method according to an embodiment of the present invention;

[0065] FIG2 is a schematic flow chart of another heat transfer parameter inversion method according to an embodiment of the present invention;

[0066] FIG3 is a schematic flow chart of another heat transfer parameter inversion method according to an embodiment of the present invention;

[0067] FIG4 is a schematic flow chart of another heat transfer parameter inversion method according to an embodiment of the present invention;

[0068] FIG5 is a schematic flow chart of a heat transfer parameter inversion method according to an embodiment of the present invention;

[0069] FIG6 is a schematic structural diagram of a target fractured aquifer according to an embodiment of the present invention;

[0070] 7 is a schematic diagram showing the fitting effect between the parameter inversion method according to an embodiment of the present invention and the three-stage single-well injection and pumping test data;

[0071] FIG8 is a structural block diagram of a heat transfer parameter inversion device according to an embodiment of the present invention;

[0072] FIG9 is a schematic diagram of the hardware structure of a computer device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0073] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of the present invention.

[0074] Compared to other methods for estimating heat transfer in aquifers, three-stage single-well injection and pumping tests are often used to invert aquifer geothermal parameters due to their low cost and high efficiency. Heat transfer parameter inversion methods primarily consist of two models: a forward model and an optimization model. Currently, numerous forward models for geothermal transfer exist, primarily including analytical and numerical solutions. The advantage of numerical models is that the corresponding mathematical models can characterize complex water flow processes. However, their drawbacks are also significant: they are computationally intensive and, when convection dominates, numerical errors such as numerical dispersion and fluctuations are difficult to eliminate. Analytical models offer low computational effort and high accuracy, and therefore are primarily used in parameter inversion methods to simulate geothermal transfer processes. Both analytical and numerical solutions suffer from two drawbacks: First, perhaps to reduce computational effort, they assume a linear relationship between geothermal diffusion and flow velocity. In reality, depending on the lithology of the formation, this relationship can be nonlinear, resulting in existing models being unable to accurately characterize heat transfer processes in aquifers. Second, the thermal mixing process within the wellbore is weakened, resulting in the inability of existing models to accurately depict the heat exchange process in the wellbore. These two assumptions may affect the accuracy of the heat transfer parameter inversion method.

[0075] In view of the shortcomings of the above methods, an embodiment of the present invention provides a heat transfer parameter inversion method.

[0076] According to an embodiment of the present invention, an embodiment of a heat transfer parameter inversion method is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0077] In this embodiment, a heat transfer parameter inversion method is provided, which can be used in the above-mentioned mobile terminal, such as a mobile phone, a tablet computer, etc. FIG1 is a flow chart of a heat transfer parameter inversion method according to an embodiment of the present invention. As shown in FIG1 , the flow chart includes the following steps:

[0078] Step S101: Obtain target area drilling data and target area hydrogeological data, conduct a three-stage single well injection and pumping test based on the target area drilling data and target area hydrogeological data, and determine the influencing parameters of the wellbore thermal mixing process.

[0079] Step S102 : constructing a mathematical model of a single-well injection and pumping test taking into account the wellbore thermal mixing process based on the influencing parameters of the wellbore thermal mixing process.

[0080] Specifically, the Green's function method is used to derive the analytical solution of a three-stage single-well injection and pumping test considering the wellbore thermal mixing process.

[0081] Step S103 , solving the mathematical model of the single-well injection and pumping test considering the wellbore thermal mixing process, and generating an analytical solution for the three-stage single-well injection and pumping test.

[0082] In step S104, an optimization objective function is constructed based on the analytical solution of the three-stage single-well injection and pumping test, and parameter inversion is performed using the optimization objective function to generate heat transfer parameter values ​​of the target fractured aquifer; wherein the heat transfer parameter values ​​of the target fractured aquifer are used to evaluate geothermal resources.

[0083] Specifically, the analytical formula is combined with the optimization model, and then the numerical calculation is implemented based on MATLAB (a commercial mathematical software) or the Mathematica platform (a scientific computing software that well combines numerical and symbolic computing engines, graphics systems, programming languages, text systems and advanced connections with other applications). By fitting the single-well injection and pumping test, the objective function is minimized, and the inverse geothermal parameters are within a given range. At this time, the inverse value is the parameter of the target aquifer, that is, the heat transfer parameter value of the target fracture aquifer.

[0084] This embodiment provides a heat transfer parameter inversion method. This method takes into account the wellbore thermal mixing process by constructing a mathematical model for a single-well injection and pumping test. The mathematical model for the single-well injection and pumping test taking into account the wellbore thermal mixing process is solved to generate an analytical solution for the three-stage single-well injection and pumping test. An optimization objective function is then constructed based on the analytical solution for the three-stage single-well injection and pumping test. This method can be used to invert and set key parameters in a heat transfer model in a fractured aquifer. It can solve the problem of parameter identification in the numerical simulation of heat transfer in fractured aquifers, improve the accuracy and computational efficiency of parameter inversion, and provide technical support for the spatial distribution assessment of geothermal resources and the efficient development of geothermal resources.

[0085] In this embodiment, a heat transfer parameter inversion method is provided, which can be used in the above-mentioned mobile terminal, such as a mobile phone, a tablet computer, etc. FIG2 is a flow chart of a heat transfer parameter inversion method according to an embodiment of the present invention. As shown in FIG2 , the flow chart includes the following steps:

[0086] Step S201: Obtain target area drilling data and target area hydrogeological data, conduct a three-stage single well injection and pumping test based on the target area drilling data and target area hydrogeological data, and determine the influencing parameters of the wellbore thermal mixing process.

[0087] Specifically, the above step S201 includes:

[0088] Step S2011: determining the target fractured aquifer and geothermal injection well based on the target area drilling data and the target area hydrogeological data.

[0089] Specifically, through the drilling data and hydrogeological data of the target area, the main strata in the target area and the spatial distribution of these strata are identified. Then, for each set of strata, the aquifer with small thickness variation, complete caprock, and complete wellbore penetration of the fracture is selected as the target fracture aquifer.

[0090] Furthermore, according to the hydrogeological conditions, complete wells with good caprocks in independent hydrogeological units are selected as geothermal injection wells.

[0091] Step S2012: measure the target fractured aquifer and geothermal injection well respectively to determine the bedrock thickness and wellbore radius.

[0092] Step S2013: Obtain the lithology of the target fractured aquifer, and determine the range of geothermal heat transfer parameters based on the lithology of the target fractured aquifer.

[0093] Among them, geothermal transfer parameters include: volume specific heat capacity of bedrock medium, thermal conductivity coefficient of bedrock medium, volume specific heat capacity of target fracture aquifer, porosity of target fracture aquifer, thermal diffusion of target fracture aquifer, width of target fracture aquifer, thermal conductivity coefficient of target fracture aquifer, and volume specific heat capacity of water.

[0094] Furthermore, for each set of strata, according to the lithology of the target fractured aquifer, the range of the parameters of geothermal transmission of the lithology of the strata is determined by consulting literature or conducting indoor experiments.

[0095] Step S2014, obtain the temperature of the target fractured aquifer, and carry out a three-stage single-well injection and pumping test based on the temperature of the target fractured aquifer to determine the injection flow rate, pumping flow rate, liquid volume in the geothermal injection well, temperature in the geothermal injection well and temperature of the injected water body; wherein, the three-stage single-well injection and pumping test includes a single-well injection and pumping test in the injection stage, the rest stage and the pumping stage.

[0096] Specifically, before conducting the test, a temperature sensor is installed in the wellbore of the selected geothermal injection well to record the temperature, which represents the temperature of the target fracture aquifer. A certain amount of water is prepared, the volume of which is 30 times higher than the volume of the wellbore, and the temperature can be 10 degrees Celsius higher or lower than the original target fracture aquifer temperature. Then, a three-stage single-well injection and pumping test is carried out to monitor the temperature of the groundwater in the wellbore.

[0097] Furthermore, the steps of the three-stage single-well injection and pumping test include: injection stage: injecting the prepared hot water or cold water into the target fractured aquifer through the selected geothermal injection well, and the volume of hot water or cold water injected into the wellbore per unit time through pumps and other equipment is the injection flow rate, and this process is the first stage; rest stage: after all the prepared hot water or cold water is injected, turn off the injection pump, wait for a period of time, and allow the water level in the injection well to recover, and this process is the second stage; extraction stage: adjust the injection pump to pump water, and extract the hot water / cold water injected into the target fractured aquifer. When the water temperature of the final extracted water is consistent with the water temperature in the original fractured aquifer, the test is ended, and this process is the third stage.

[0098] Among them, since there is a certain volume of groundwater in the geothermal injection well before the test (i.e., the volume of groundwater before mixing), this part of water will change its temperature at the initial stage of hot water or cold water injection, causing the groundwater temperature in the well at the initial stage of the test to gradually increase from the original formation temperature to the temperature value of the injected hot water or cold water. This process is called the wellbore thermal mixing process in this patent.

[0099] This embodiment provides a heat transfer parameter inversion method that calculates relevant data of the target fractured aquifer and geothermal injection well to determine the influencing parameters of the wellbore thermal mixing process. This lays the foundation for the subsequent mathematical model of single-well injection and pumping tests that consider the wellbore thermal mixing process. The range of geothermal transfer parameters also lays the foundation for the accuracy judgment of the heat transfer parameter values ​​of the target fractured aquifer generated by subsequent inversion.

[0100] Step S202: Based on the influencing parameters of the wellbore thermal mixing process, a mathematical model of a single-well injection and pumping test considering the wellbore thermal mixing process is constructed. For details, please refer to step S102 of the embodiment shown in FIG1 , which will not be described in detail here.

[0101] Step S203: Solve the mathematical model of the single-well injection and pumping test considering the wellbore thermal mixing process to generate a three-stage single-well injection and pumping test analytical solution. For details, please refer to step S103 of the embodiment shown in FIG1 , which will not be repeated here.

[0102] Step S204: Solve the mathematical model of the single-well injection and pumping test considering the wellbore thermal mixing process to generate a three-stage single-well injection and pumping test analytical solution. For details, please refer to step S104 of the embodiment shown in FIG1 , which will not be repeated here.

[0103] The present embodiment provides a heat transfer parameter inversion method that solves the problem of parameter identification during heat transfer numerical simulation by inverting key heat transfer parameters, such as the thermal expansion coefficient and the thermal diffusion coefficient.

[0104] In this embodiment, a heat transfer parameter inversion method is provided, which can be used in the above-mentioned mobile terminal, such as a mobile phone, a tablet computer, etc. FIG3 is a flow chart of a heat transfer parameter inversion method according to an embodiment of the present invention. As shown in FIG3 , the flow chart includes the following steps:

[0105] Step S301: Obtain borehole data and hydrogeological data for the target area. Based on this data, conduct a three-stage single-well injection and pumping test to determine parameters influencing the wellbore thermal mixing process. For details, see step S201 in the embodiment shown in Figure 2 and will not be repeated here.

[0106] Step S302 : constructing a mathematical model of a single-well injection and pumping test taking into account the wellbore thermal mixing process based on the influencing parameters of the wellbore thermal mixing process.

[0107] Specifically, the above step S302 includes:

[0108] Step S3021 : constructing an injection phase mixing effect model, a rest phase mixing effect model, and an extraction phase mixing effect model based on the influencing parameters of the wellbore thermal mixing process.

[0109] In some optional implementations, step S3021 includes:

[0110] Step a1: constructing a mixed effect model for the injection phase based on the volumetric specific heat capacity of water, the liquid volume in the geothermal injection well during the injection phase, the temperature in the geothermal injection well, the injection flow rate, and the temperature of the injected water.

[0111] Specifically, the expression of the mixed effect model in the injection phase is as follows: T w (t=0)=T0 (2)

[0112] In the above formula, ρ w c w represents the volume specific heat capacity of water, ρ w represents the density of water, c w represents the specific heat capacity of water, V w,inj represents the liquid volume in the geothermal injection well during the injection phase, T w (t) represents the temperature in the geothermal injection well, Q inj Indicates the water injection flow rate, T inj represents the temperature of the injected water (i.e., the temperature of the injected hot or cold water), T0 represents the initial temperature in the fracture and bedrock medium, t represents the time, t inj Indicates the time of the injection phase.

[0113] Step a2: constructing a resting phase mixed effect model based on the temperature in the geothermal injection well and the temperature of the target fractured aquifer.

[0114] Specifically, the expression of the mixed effect model for the rest phase is as follows:

[0115] In the above formula, t res represents the rest period, T f (x, t) represents the temperature of the target fracture aquifer, and x represents the horizontal position.

[0116] In step a3, a mixed effect model for the extraction phase is constructed based on the pumping flow rate, the volumetric specific heat capacity of water, the liquid volume in the geothermal injection well during the extraction phase, the temperature in the geothermal injection well, the width of the target fractured aquifer, the bedrock thickness, the thermal conductivity coefficient of the target fractured aquifer, and the temperature of the target fractured aquifer.

[0117] Specifically, the expression of the mixed effect model in the extraction stage is as follows:

[0118] In the above formula, V w,ext represents the liquid volume in the geothermal injection well during the extraction phase, b represents the width of the target fracture aquifer, B represents the bedrock thickness, and k f represents the thermal conductivity of the target fractured aquifer, t ext Indicates the time of the extraction phase.

[0119] Step S3022: constructing a control equation based on the influencing parameters of the wellbore thermal mixing process; wherein the control equation includes a fracture medium heat transfer kinetic equation and a bedrock medium heat transfer kinetic equation.

[0120] In some optional implementations, step S3022 includes:

[0121] Step b1, obtain the temperature of the bedrock medium and the flow rate of the target fractured aquifer, and construct a fractured medium heat transfer kinetic equation based on the volume specific heat capacity of the target fractured aquifer, the temperature of the target fractured aquifer, the thermal conductivity coefficient of the target fractured aquifer, the thermal diffusion coefficient of the target fractured aquifer, the volume specific heat capacity of water, the porosity of the target fractured aquifer, the thermal conductivity coefficient of the bedrock medium, the width of the target fractured aquifer, the temperature of the bedrock medium and the flow rate of the target fractured aquifer.

[0122] Specifically, the expression of the heat transfer kinetic equation of fracture medium is as follows:

[0123] In the above formula, ρ f c f represents the volume specific heat capacity of the target fractured aquifer, ρ f represents the density of the target fractured aquifer, cf represents the specific heat capacity of the target fracture aquifer, α represents the thermal diffusion of the target fracture aquifer, v represents the flow velocity of the target fracture aquifer, mm is a constant (its value is 1 to 2), φ f represents the porosity of the target fractured aquifer, T m (x,z,t) represents the temperature of the bedrock medium, k m represents the thermal conductivity of the bedrock medium, and z represents the vertical position.

[0124] Furthermore, during the injection phase, the flow rate of the target fractured aquifer is calculated as follows:

[0125] In the above formula, Q inj Indicates the water injection flow rate.

[0126] Furthermore, during the extraction phase, the flow rate of the target fractured aquifer is calculated as follows:

[0127] In the above formula, Q ext Indicates the extraction flow.

[0128] Step b2: constructing a bedrock medium heat transfer kinetic equation based on the volume specific heat capacity of the bedrock medium, the temperature of the bedrock medium, and the thermal conductivity coefficient of the bedrock medium.

[0129] Specifically, the expression of the bedrock medium heat transfer kinetic equation is as follows:

[0130] In the above formula, ρ m c m represents the volume specific heat capacity of the bedrock medium, ρ m represents the density of the bedrock medium, c m Represents the specific heat capacity of the bedrock medium.

[0131] Step S3023: determining initial conditions and boundary conditions based on the influencing parameters of the wellbore thermal mixing process.

[0132] In some optional implementations, step S3023 includes:

[0133] Step c1, obtaining the initial temperature in the fracture and bedrock medium, and constructing initial conditions based on the temperature of the target fracture aquifer, the temperature of the bedrock medium, and the initial temperature in the fracture and bedrock medium.

[0134] Specifically, the initial conditions are as follows: T f (x, t=0)=T m (x,z,t=0)=T0 (11)

[0135] Step c2: constructing boundary conditions based on the temperature of the target fractured aquifer, the temperature of the bedrock medium, the temperature in the geothermal injection well, and the initial temperatures in the fracture and bedrock medium.

[0136] Specifically, the boundary conditions include the wellbore outer boundary conditions and the wellbore inner boundary conditions, wherein the expression of the wellbore outer boundary condition at the horizontal position is as follows: f (x→∞,t)=T0,t>0 (12)

[0137] Furthermore, the expression of the outer boundary condition of the vertical position of the wellbore is as follows: m (Z→∞,t)=T0,t>0 (13)

[0138] Furthermore, the expression of the boundary condition inside the wellbore is as follows: f (x=0,t)=T w (t), t>0 (14) T f (x,t)=T m (x,z=0,t),t>0 (15)

[0139] Step S3024: determining the effective thermal diffusion coefficient based on the influencing parameters of the wellbore thermal mixing process.

[0140] Specifically, the effective thermal diffusion coefficient is determined based on the thermal conductivity of the target fractured aquifer, the volumetric specific heat capacity of the target fractured aquifer, the thermal diffusivity of the target fractured aquifer, the volumetric specific heat capacity of water, and the flow velocity of the target fractured aquifer. The expression of the effective thermal diffusion coefficient D is as follows:

[0141] Step S3025: A mathematical model of a single-well injection-extraction test considering the wellbore thermal mixing process is constructed based on the heat transfer kinetic equation, initial conditions, boundary conditions, effective thermal diffusion coefficient, injection phase mixing effect model, rest phase mixing effect model, and extraction phase mixing effect model.

[0142] Step S303 , solving the mathematical model of the single-well injection and pumping test considering the wellbore thermal mixing process, and generating an analytical solution for the three-stage single-well injection and pumping test.

[0143] Specifically, the analytical solution for the injection phase in the three-stage single-well injection and pumping test is:

[0144] Where exp(·) represents the exponential function, represents the temperature in the bedrock medium in Laplace space, represents the temperature in the fracture medium in Laplace space, s represents the Laplace variable, αinj represents the first parameter, β represents the second parameter, δ represents the third parameter, x D represents the dimensionless distance, θ represents the fourth parameter, where

[0145] Furthermore, the analytical solution for the rest phase in the three-stage single-well injection and pumping test is: f(η)=θT mD (t injD )-θs(δ1+δ2η) (31)

[0146] Where η is the Green function g(z D ,θs;η), χ represents the Green function G1(x D ,s;χ) integral variable, z eD represents the distance between the outer boundary of the bedrock and the crack, and f(η) represents g(z D ,θs;η) is a function of the integral variable, δ1 represents the fifth parameter, δ2 represents the sixth parameter, z D represents dimensionless distance, f0(χ) represents G1(x D ,s;χ) function of the integral variable, T mD represents the dimensionless temperature in the bedrock medium, t injD represents the dimensionless injection time, C1, C2 and C3 represent the coefficients of the Green's function (determined by Equations 36-37), T fD represents the dimensionless temperature in the fracture medium, where f0(χ) = βT fD (t injD ) (33)

[0147] Furthermore, the analytical solution for the extraction phase in the three-stage single-well injection and extraction test is:

[0148] in, is the Green function The integral variable, is the Green function The integral variable, and Represents two Green functions with different coefficients and kernel functions, express Function of the integral variable, express Function of the integral variable, a1 represents the seventh parameter, b1 represents the eighth parameter, m represents the ninth parameter, n represents the tenth parameter, D1, D2, D2, D3, E1, E1, E2 and E4 represent the coefficients of the Green's function, t D represents dimensionless time, t resD represents the dimensionless rest time, ε represents the eleventh parameter, T fD represents the dimensionless temperature in the fractured medium, where m=-nx eD (46) D1=-D2 (48) E1=WE2 (51)

[0149] in, Represents the dimensionless temperature of the injection and pumping test.

[0150] In step S304, an optimization objective function is constructed based on the analytical solution of the three-stage single-well injection and pumping test. Parameter inversion is performed using this optimization objective function to generate heat transfer parameter values ​​for the target fractured aquifer. These heat transfer parameter values ​​for the target fractured aquifer are used to assess geothermal resources. For details, see step S204 in the embodiment shown in Figure 2 and will not be repeated here.

[0151] This embodiment provides a heat transfer parameter inversion method. Existing analytical solutions for three-stage single-well injection and pumping geothermal transfer all assume a linear relationship between geothermal diffusion and flow velocity, an assumption that often violates actual physical laws. This embodiment considers the nonlinear relationship between heat diffusion and flow velocity in the construction of a mathematical model for a single-well injection and pumping test that takes into account the wellbore thermal mixing process, thereby improving the simulation capability of the heat transfer process in fractured aquifers and the accuracy of heat transfer parameter inversion.

[0152] In this embodiment, a heat transfer parameter inversion method is provided, which can be used in the above-mentioned mobile terminal, such as a mobile phone, a tablet computer, etc. FIG4 is a flow chart of a heat transfer parameter inversion method according to an embodiment of the present invention. As shown in FIG4 , the flow chart includes the following steps:

[0153] Step S401: Obtain borehole data and hydrogeological data for the target area. Based on this data, conduct a three-stage single-well injection and pumping test to determine parameters influencing the wellbore thermal mixing process. For details, see step S301 in the embodiment shown in Figure 3 and will not be repeated here.

[0154] Step S402: Based on the influencing parameters of the wellbore thermal mixing process, a mathematical model of a single-well injection and pumping test considering the wellbore thermal mixing process is constructed. For details, please refer to step S302 of the embodiment shown in FIG3 , which will not be described in detail here.

[0155] Step S403: Solve the mathematical model of the single-well injection and pumping test considering the wellbore thermal mixing process to generate an analytical solution for the three-stage single-well injection and pumping test. For details, please refer to step S303 of the embodiment shown in FIG3 , which will not be described in detail here.

[0156] In step S404, an optimization objective function is constructed based on the analytical solution of the three-stage single-well injection and pumping test, and parameter inversion is performed using the optimization objective function to generate heat transfer parameter values ​​for the target fractured aquifer; wherein the heat transfer parameter values ​​for the target fractured aquifer are used to evaluate geothermal resources.

[0157] Specifically, the above step S404 includes:

[0158] Step S4041 , based on the analytical solution of the three-stage single-well injection and pumping test, an optimization objective function is constructed with the goal of minimizing the fitting value of the three-stage single-well injection and pumping test.

[0159] In some optional implementations, the above step S4041 includes:

[0160] Step d1: Determine the simulated value of the sampling point based on the analytical solution of the three-stage single-well injection and pumping test.

[0161] Step d2: Obtain the observed values ​​of the sampling points, and determine the mean square error value of the three-stage single-well injection and pumping test based on the simulated values ​​and the observed values ​​of the sampling points.

[0162] Specifically, the calculation formula for the mean square error of the three-stage single-well injection and pumping test is as follows:

[0163] In the above formula, p1~p L Indicates the parameters to be determined, L indicates the number of parameters to be determined, j indicates the number of sampling points in the iteration process, i indicates the stage, is the observed value or reference value of the j-th sampling point, is the simulated value of the jth sampling point, which is calculated by the above formula (17)-formula (54), and N represents the total number of sampling points.

[0164] Step d3, obtaining the weighting coefficient of the three-stage single-well injection and pumping test, and constructing an optimization objective function based on the mean square error value of the three-stage single-well injection and pumping test and the weighting coefficient of the three-stage single-well injection and pumping test.

[0165] Specifically, the expression of the optimization objective function is as follows:

[0166] In the above formula, F represents the optimization objective function, μ i represents the weighting coefficient of the i-th stage, Δf i represents the mean square error value of the i-th stage, and u represents the number of stages in the single-well injection and pumping test.

[0167] Step S4042: Solve the optimization objective function to generate heat transfer parameter values ​​for the target fractured aquifer.

[0168] Specifically, the optimization objective function is solved based on the MATLAB (a commercial mathematical software) or Mathematica (a scientific computing software that well combines numerical and symbolic computing engines, graphics systems, programming languages, text systems, and advanced connections with other applications) platform to generate the heat transfer parameter values ​​of the target fractured aquifer.

[0169] Furthermore, the heat transfer parameter value of the target fractured aquifer is compared with the range of the geothermal heat transfer parameter, and when the heat transfer parameter value of the target fractured aquifer meets the range of the geothermal heat transfer parameter, the heat transfer parameter value of the target fractured aquifer is output.

[0170] This embodiment provides a heat transfer parameter inversion method that combines an optimization objective function to invert key geothermal parameters, greatly improving the efficiency of parameter inversion. Moreover, compared with existing methods, it is more convenient for engineering promotion and application, providing technical support for the evaluation of the mining potential and development and utilization efficiency of geothermal resources.

[0171] The steps of a heat transfer parameter inversion method are described below through a specific embodiment.

[0172] Example 1

[0173] As shown in Figure 5, the steps of the inversion method for heat transfer parameters in fractured aquifers considering the wellbore thermal mixing process are as follows:

[0174] Step 1: Determine the target fractured aquifer using borehole data and hydrogeological data from the study area. Also, select intact wells with good caprocks in independent hydrogeological units as geothermal injection wells based on the hydrogeological conditions.

[0175] Step 2: Determine the range of geothermal heat transfer parameters based on the lithology of the target fractured aquifer;

[0176] Step 3: Measure the temperature of the target fractured aquifer, prepare hot or cold water 30 times the volume of the wellbore, and ensure that the temperature of the prepared hot or cold water is 10 degrees higher or lower than the original target fractured aquifer temperature. Conduct a three-stage single-well injection and pumping test to monitor the temperature of the groundwater in the wellbore.

[0177] Step 4: Based on the key parameters affecting the wellbore thermal mixing process obtained in step 3, a mathematical model for the single-well injection and pumping test is constructed that considers the wellbore thermal mixing process and the nonlinear relationship between heat diffusion and flow rate;

[0178] Step 5: Based on step 3, the Green function method is used to derive the analytical solution of the single-well injection and pumping test considering the wellbore thermal mixing process;

[0179] Step 6: Combine the analytical formula with the optimization model, and then perform numerical calculations based on the MATLAB or Mathematica platform. By fitting the single-well injection and pumping test, the objective function is minimized, and the inverse geothermal parameters are within a given range. At this point, the inverse value is the parameter of the target aquifer.

[0180] Example 2

[0181] In order to verify the accuracy of the inversion method for heat transfer parameters of fractured aquifers considering the wellbore thermal mixing process, it is assumed that the heat transfer parameter values ​​of the target fractured aquifer are known, and then numerical simulation software is used to construct numerical values ​​instead of actual observation data for illustration.

[0182] A numerical model was constructed for the fractured aquifer structure shown in Figure 6. The constructed numerical model was used to calculate data from three-stage single-well injection and pumping tests. These calculated data served as reference values. Based on these reference values, the method of the present invention was used to invert key heat transfer parameters. In Figure 6, 1 represents the width of the fractured aquifer; X and Z represent the constructed coordinate system; 2 represents the fractured aquifer, which serves as the flow channel for hot or cold water injected into the injection well; 3 represents the flow rate of hot or cold water injected during the injection phase and the pumping rate during the pumping phase; 4 represents the injection wellbore, whose main function is to generate the wellbore thermal mixing process; 5 represents the diameter of the wellbore; 6 represents the water filter on the wellbore wall, through which the fluid in the wellbore and the fractured aquifer are exchanged; and 7 represents the aquifer thickness.

[0183] Construct a numerical model of the fractured aquifer structure as shown in FIG6: In this embodiment, COMSOL numerical simulation software (a multi-physics simulation software) is used to construct the fractured aquifer structure as shown in FIG6 to simulate the three-stage single well injection and pumping test. The length, width and height of the constructed numerical model are 15m, 10m and 5m respectively, and the wellbore radius r w = 0.25m, the thickness of the fractured aquifer is 0.25m, and the thickness of the bedrock medium is 5m. The numerical model is divided into 882579 grids, and the results are consistent with 8825790 grids. The numerical error can be ignored. The basic thermal parameters used in the numerical model are: ρ w c w =4.2×10 6 J / (m 3 ·℃), ρ f c f =2.65×10 6 J / (m 3 ·℃), ρ m c m =2.38×10 6 J / (m 3 ℃), k f =2.3W / (m·℃),k m =1.8W / (m·℃), α=0.1m, T inj =30℃, T0=10℃, φ f =0.38, Q inj =50m 3 / d,Q ext =45m 3 / d,V w,inj =39m 3 , V w,ext =35m 3 , mm = 2, t inj =250h, t res =50h,t ext =400h, b=0.25m, B=5.0m. Among them, J / (m 3 ·℃) is joule / (cubic meter·degrees Celsius), W / (m·℃) is watt / (meter·degrees Celsius), m 3 / d is cubic meters per day, and h is hour.

[0184] In this simulation, the middle position inside the wellbore was selected to obtain the reference benchmark value, and the obtained reference benchmark value was expressed in normalized temperature.

[0185] Based on the results of the three-stage single-well injection and pumping test simulated by the numerical model, the specific implementation steps of the technical solution of the present invention are as follows:

[0186] In step 1, the basic parameters of the injection well can be determined based on the constructed numerical model: well radius r w =0.25m, the volume of fluid in the wellbore during the injection and extraction stages: V w,inj =39m 3 and V w,ext =35m 3 ;

[0187] In step 2, the basic heat transport parameters of the fractured aquifer can be determined based on the constructed numerical model: ρ w c w =4.2×10 6 J / (m 3 ·℃), ρ f c f =2.65×10 6 J / (m 3 ·℃), ρ m c m =2.38×10 6 J / (m 3 ℃), k f =2.3W / (m·℃),k m =1.8W / (m·℃), α=0.1m, b=0.25m, B=5.0m, φ f =0.38;

[0188] In step 3, the target fracture aquifer temperature determined based on the constructed numerical model is T0 = 10 °C, and the prepared hot water temperature is T inj =30℃, the flow rate and duration of each stage of the three-stage single-well injection and pumping test are: Q inj =50m 3 / d,Q ext =45m 3 / d,t inj =250h, t res =50h,t ext =400h;

[0189] In step 4, the coefficient describing the nonlinear relationship between heat diffusion and flow rate is set to: mm = 2;

[0190] The optimization objective function was written in MATLAB, and the key thermal attribute parameter k of the target fractured aquifer was inverted by fitting the single well injection and pumping test data (the benchmark reference value calculated by the numerical model). f , α and k m , so that the objective function reaches the minimum value. In this embodiment, when the objective function F≤1E-5, the thermal property parameter k output by the method of the present invention is f , α and k m The value is the inversion result.

[0191] In this embodiment, after optimizing the fitting between the method of the present invention and the reference values ​​calculated by the numerical model, the inversion results of the key thermal property parameters are: k f =2.28W / (m·℃),k m =1.81W / (m·℃) and α=0.1m, the fitting results are shown in Figure 7.

[0192] The results in FIG7 show that the parameter inversion method of the present invention can well explain the reference value / observation value, proving that the method of the present invention can effectively invert the key parameters of heat transfer, indicating that the method of the present invention can solve the problem of parameter identification in the process of numerical simulation of heat transfer.

[0193] This embodiment also provides a heat transfer parameter inversion device for implementing the above-mentioned embodiments and preferred embodiments. Details already described will not be repeated here. As used below, the term "module" may refer to a combination of software and / or hardware that implements a predetermined function. Although the devices described in the following embodiments are preferably implemented in software, implementation using hardware, or a combination of software and hardware, is also possible and contemplated.

[0194] This embodiment provides a heat transfer parameter inversion device, as shown in FIG8 , comprising:

[0195] An acquisition module 801 is configured to acquire borehole data and hydrogeological data of a target area, conduct a three-stage single-well injection and pumping test based on the borehole data and hydrogeological data of the target area, and determine parameters influencing the wellbore thermal mixing process;

[0196] A construction module 802 is used to construct a mathematical model of a single-well injection and pumping test considering the wellbore thermal mixing process based on the influencing parameters of the wellbore thermal mixing process;

[0197] The solution module 803 is used to solve the mathematical model of the single-well injection and pumping test considering the wellbore thermal mixing process, and generate an analytical solution for the three-stage single-well injection and pumping test;

[0198] Inversion module 804 is used to construct an optimization objective function based on the analytical solution of the three-stage single-well injection and pumping test, and use the optimization objective function to perform parameter inversion to generate heat transfer parameter values ​​of the target fractured aquifer; wherein the heat transfer parameter values ​​of the target fractured aquifer are used to evaluate geothermal resources.

[0199] In some optional implementations, the acquisition module 801 includes:

[0200] A first determination submodule is used to determine the target fractured aquifer and geothermal injection well based on the target area drilling data and the target area hydrogeological data;

[0201] The measurement submodule is used to measure the target fractured aquifer and geothermal injection well respectively to determine the bedrock thickness and wellbore radius;

[0202] a second determination submodule, configured to obtain the lithology of the target fractured aquifer and determine a range of geothermal heat transfer parameters based on the lithology of the target fractured aquifer;

[0203] The test submodule is used to obtain the temperature of the target fractured aquifer, and conduct a three-stage single-well injection and pumping test based on the temperature of the target fractured aquifer to determine the injection flow rate, pumping flow rate, liquid volume in the geothermal injection well, temperature in the geothermal injection well, and temperature of the injected water body; among them, the three-stage single-well injection and pumping test includes single-well injection and pumping tests in the injection stage, rest stage, and pumping stage.

[0204] In some optional embodiments, the geothermal heat transfer parameter in the range of geothermal heat transfer parameters includes:

[0205] Volumetric specific heat capacity of bedrock medium, thermal conductivity coefficient of bedrock medium, volumetric specific heat capacity of target fractured aquifer, porosity of target fractured aquifer, thermal diffusion of target fractured aquifer, width of target fractured aquifer, thermal conductivity coefficient of target fractured aquifer, and volumetric specific heat capacity of water.

[0206] In some optional implementations, building module 802 includes:

[0207] The first construction submodule is used to respectively construct an injection phase mixed effect model, a rest phase mixed effect model and an extraction phase mixed effect model based on the influencing parameters of the wellbore thermal mixing process;

[0208] The second construction submodule is used to construct a control equation based on the influencing parameters of the wellbore thermal mixing process; wherein the control equation includes a thermal transfer kinetic equation of the fracture medium and a thermal transfer kinetic equation of the bedrock medium;

[0209] A third determination submodule is configured to determine initial conditions and boundary conditions based on influencing parameters of the wellbore thermal mixing process;

[0210] a fourth determination submodule, configured to determine an effective thermal diffusion coefficient based on influencing parameters of a wellbore thermal mixing process;

[0211] The third construction submodule is used to construct a mathematical model of a single-well injection and extraction test considering the wellbore thermal mixing process based on the heat transfer kinetic equation, initial conditions, boundary conditions, effective thermal diffusion coefficient, injection stage mixing effect model, rest stage mixing effect model and extraction stage mixing effect model.

[0212] In some optional embodiments, the first building block includes:

[0213] A first construction unit is used to construct an injection phase mixed effect model based on the volumetric specific heat capacity of water, the liquid volume in the geothermal injection well during the injection phase, the temperature in the geothermal injection well, the injection flow rate, and the temperature of the injected water body;

[0214] a second construction unit for constructing a rest phase mixed effect model based on the temperature in the geothermal injection well and the temperature of the target fractured aquifer;

[0215] The third construction unit is used to construct a mixed effect model in the extraction stage based on the pumping flow rate, the volumetric specific heat capacity of water, the liquid volume in the geothermal injection well during the extraction stage, the temperature in the geothermal injection well, the width of the target fractured aquifer, the bedrock thickness, the thermal conductivity coefficient of the target fractured aquifer, and the temperature of the target fractured aquifer.

[0216] In some optional embodiments, the second building block includes:

[0217] a fourth construction unit, configured to obtain the temperature of the bedrock medium and the flow velocity of the target fractured aquifer, and construct a fractured medium heat transfer kinetic equation based on the volumetric specific heat capacity of the target fractured aquifer, the temperature of the target fractured aquifer, the thermal conductivity coefficient of the target fractured aquifer, the thermal diffusivity of the target fractured aquifer, the volumetric specific heat capacity of water, the porosity of the target fractured aquifer, the thermal conductivity coefficient of the bedrock medium, the width of the target fractured aquifer, the temperature of the bedrock medium, and the flow velocity of the target fractured aquifer;

[0218] The fifth construction unit is used to construct a bedrock medium heat transfer kinetic equation based on the volume specific heat capacity of the bedrock medium, the temperature of the bedrock medium, and the thermal conductivity coefficient of the bedrock medium.

[0219] In some optional implementations, the third determining submodule includes:

[0220] a sixth construction unit, configured to obtain initial temperatures in the fracture and bedrock media, and construct initial conditions based on the temperature of the target fracture aquifer, the temperature of the bedrock media, and the initial temperatures in the fracture and bedrock media;

[0221] The seventh construction unit is used to construct boundary conditions based on the temperature of the target fracture aquifer, the temperature of the bedrock medium, the temperature in the geothermal injection well, and the initial temperature in the fracture and bedrock medium.

[0222] In some optional embodiments, the fourth determination submodule is specifically used to determine the effective thermal diffusion coefficient based on the thermal conductivity coefficient of the target fracture aquifer, the volume specific heat capacity of the target fracture aquifer, the thermal diffusivity of the target fracture aquifer, the volume specific heat capacity of water and the flow velocity of the target fracture aquifer.

[0223] In some optional embodiments, the inversion module 804 includes:

[0224] The fourth construction submodule is used to construct an optimization objective function based on the analytical solution of the three-stage single-well injection and pumping test and with the goal of minimizing the fitting value of the three-stage single-well injection and pumping test;

[0225] The solution submodule is used to solve the optimization objective function and generate the heat transfer parameter values ​​of the target fractured aquifer.

[0226] In some optional embodiments, the fourth building block includes:

[0227] The first determining unit is used to determine the simulation value of the sampling point based on the analytical solution of the three-stage single well injection and pumping test;

[0228] A second determining unit is configured to obtain an observation value of a sampling point and determine a mean square error value of the three-stage single-well injection and pumping test based on the simulation value and the observation value of the sampling point;

[0229] The eighth construction unit is used to obtain the weighting coefficient of the three-stage single-well injection and pumping test, and construct an optimization objective function based on the mean square error value of the three-stage single-well injection and pumping test and the weighting coefficient of the three-stage single-well injection and pumping test.

[0230] In some optional implementations, the expression of the optimization objective function in the eighth building block is as follows:

[0231] In the above formula, F represents the optimization objective function, μ i represents the weighting coefficient of the i-th stage, Δf i represents the mean square error value of the i-th stage, and u represents the number of stages in the single-well injection and pumping test.

[0232] In some optional embodiments, the method further includes:

[0233] The comparison module is used to compare the heat transfer parameter value of the target fractured aquifer with the range of the geothermal transfer parameter, and when the heat transfer parameter value of the target fractured aquifer meets the range of the geothermal transfer parameter, output the heat transfer parameter value of the target fractured aquifer.

[0234] The further functional description of each of the above modules and units is the same as that of the above corresponding embodiments and will not be repeated here.

[0235] In this embodiment, a heat transfer parameter inversion device is presented in the form of a functional unit, where the unit refers to an ASIC (Application Specific Integrated Circuit) circuit, a processor and memory that executes one or more software or fixed programs, and / or other devices that can provide the above functions.

[0236] An embodiment of the present invention further provides a computer device having a heat transfer parameter inversion device as shown in FIG8 .

[0237] Please refer to Figure 9, which is a schematic diagram of the structure of a computer device provided by an optional embodiment of the present invention. As shown in Figure 9, the computer device includes: one or more processors 10, a memory 20, and interfaces for connecting various components, including high-speed interfaces and low-speed interfaces. The various components are connected to each other using different buses and can be installed on a common motherboard or installed in other ways as needed. The processor can process instructions executed within the computer device, including instructions stored in or on the memory to display graphical information of a GUI on an external input / output device (such as a display device coupled to the interface). In some optional embodiments, if necessary, multiple processors and / or multiple buses can be used together with multiple memories and multiple memories. Similarly, multiple computer devices can be connected, with each device providing some of the necessary operations (for example, as a server array, a group of blade servers, or a multi-processor system). Figure 9 uses a processor 10 as an example.

[0238] The processor 10 may be a central processing unit, a network processor, or a combination thereof. The processor 10 may further include a hardware chip. The hardware chip may be an application-specific integrated circuit, a programmable logic device, or a combination thereof. The programmable logic device may be a complex programmable logic device, a field programmable gate array, a general purpose array logic, or any combination thereof.

[0239] The memory 20 stores instructions that can be executed by at least one processor 10, so that the at least one processor 10 executes the method shown in the above embodiment.

[0240] The memory 20 may include a program storage area and a data storage area, wherein the program storage area may store an operating system and application programs required for at least one function; the data storage area may store data created based on the use of the computer device, etc. In addition, the memory 20 may include a high-speed random access memory, and may also include a non-transient memory, such as at least one disk storage device, a flash memory device, or other non-transient solid-state storage device. In some optional embodiments, the memory 20 may optionally include a memory remotely located relative to the processor 10, and these remote memories may be connected to the computer device via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0241] The memory 20 may include a volatile memory, such as a random access memory; the memory may also include a non-volatile memory, such as a flash memory, a hard disk or a solid-state drive; the memory 20 may also include a combination of the above types of memory.

[0242] The computer device further includes an input device 30 and an output device 40. The processor 10, the memory 20, the input device 30 and the output device 40 may be connected via a bus or other means, and FIG9 shows a bus connection as an example.

[0243] The input device 30 can receive input digital or character information and generate key signal input related to user settings and function control of the computer device, such as a touch screen, a keypad, a mouse, a trackpad, a touch pad, an indicator stick, one or more mouse buttons, a trackball, a joystick, etc. The output device 40 can include a display device, an auxiliary lighting device (e.g., an LED), and a tactile feedback device (e.g., a vibration motor). The above-mentioned display device includes but is not limited to a liquid crystal display, a light emitting diode, a display, and a plasma display. In some optional embodiments, the display device can be a touch screen.

[0244] The embodiment of the present invention also provides a computer-readable storage medium. The above-mentioned method according to the embodiment of the present invention can be implemented in hardware, firmware, or implemented as a computer code that can be recorded in a storage medium, or implemented as a computer code that is originally stored in a remote storage medium or a non-temporary machine-readable storage medium and downloaded through a network and will be stored in a local storage medium, so that the method described herein can be stored in such software processing on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. Among them, the storage medium can be a magnetic disk, an optical disk, a read-only storage memory, a random access memory, a flash memory, a hard disk or a solid-state drive, etc.; further, the storage medium can also include a combination of the above-mentioned types of memory. It can be understood that a computer, a processor, a microprocessor controller or programmable hardware includes a storage component that can store or receive software or computer code. When the software or computer code is accessed and executed by a computer, a processor or hardware, the method shown in the above embodiment is implemented.

[0245] Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention. Such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A heat transfer parameter inversion method, characterized in that: The method comprises: Obtaining target area drilling data and target area hydrogeological data, and conducting a three-stage single well injection and pumping test based on the target area drilling data and target area hydrogeological data to determine the influencing parameters of the wellbore thermal mixing process; Based on the influencing parameters of the wellbore thermal mixing process, a mathematical model of a single well injection and pumping test considering the wellbore thermal mixing process is constructed; Solving the mathematical model of the single-well injection and pumping test considering the wellbore thermal mixing process, generating an analytical solution for the three-stage single-well injection and pumping test; An optimization objective function is constructed based on the analytical solution of the three-stage single-well injection and pumping test, and parameter inversion is performed using the optimization objective function to generate heat transfer parameter values ​​of the target fractured aquifer; wherein the heat transfer parameter values ​​of the target fractured aquifer are used to evaluate geothermal resources.

2. The method according to claim 1, characterized in that The three-stage single-well injection and pumping test is carried out based on the drilling data and hydrogeological data of the target area to determine the influencing parameters of the wellbore thermal mixing process, including: Determine a target fractured aquifer and a geothermal water injection well based on the target area drilling data and the target area hydrogeological data; Measuring the target fractured aquifer and the geothermal water injection well respectively to determine the bedrock thickness and the wellbore radius; Obtaining the lithology of the target fractured aquifer, and determining the range of geothermal transport parameters based on the lithology of the target fractured aquifer; The temperature of the target fractured aquifer is obtained, and based on the temperature of the target fractured aquifer, a three-stage single-well injection and pumping test is carried out to determine the injection flow rate, pumping flow rate, liquid volume in the geothermal injection well, temperature in the geothermal injection well and temperature of the injected water body; wherein the three-stage single-well injection and pumping test includes single-well injection and pumping tests in injection stage, rest stage and pumping stage.

3. The method according to claim 2, characterized in that The geothermal heat transfer parameters in the range of geothermal heat transfer parameters include: Volumetric specific heat capacity of bedrock medium, thermal conductivity coefficient of bedrock medium, volumetric specific heat capacity of target fractured aquifer, porosity of target fractured aquifer, thermal diffusion of target fractured aquifer, width of target fractured aquifer, thermal conductivity coefficient of target fractured aquifer, volumetric specific heat capacity of water.

4. The method according to claim 3, characterized in that The single-well injection and pumping test mathematical model considering the wellbore thermal mixing process is constructed based on the influencing parameters of the wellbore thermal mixing process, including: Based on the influencing parameters of the wellbore thermal mixing process, a mixed effect model for the injection stage, a mixed effect model for the rest stage and a mixed effect model for the extraction stage are respectively constructed; Constructing a control equation based on the influencing parameters of the wellbore thermal mixing process; wherein the control equation includes a fracture medium heat transfer kinetic equation and a bedrock medium heat transfer kinetic equation; Determining initial conditions and boundary conditions based on influencing parameters of the wellbore thermal mixing process; determining an effective thermal diffusion coefficient based on influencing parameters of the wellbore thermal mixing process; The mathematical model of the single-well injection and extraction test considering the wellbore thermal mixing process is constructed based on the heat transfer kinetic equation, the initial conditions, the boundary conditions, the effective thermal diffusion coefficient, the injection stage mixing effect model, the rest stage mixing effect model and the extraction stage mixing effect model.

5. The method according to claim 4, characterized in that The injection phase mixed effect model, the rest phase mixed effect model and the extraction phase mixed effect model are respectively constructed based on the influencing parameters of the wellbore thermal mixing process, including: Constructing the mixed effect model of the injection phase based on the volumetric specific heat capacity of the water, the liquid volume in the geothermal water injection well during the injection phase, the temperature in the geothermal water injection well, the water injection flow rate and the temperature of the injected water body; Constructing the rest phase mixed effect model based on the temperature in the geothermal water injection well and the temperature of the target fractured aquifer; The mixed effect model of the extraction stage is constructed based on the pumping flow rate, the volumetric specific heat capacity of the water, the liquid volume in the geothermal injection well during the extraction stage, the temperature in the geothermal injection well, the width of the target fractured aquifer, the bedrock thickness, the thermal conductivity coefficient of the target fractured aquifer and the temperature of the target fractured aquifer.

6. The method according to claim 4, characterized in that The control equation is constructed based on the influencing parameters of the wellbore thermal mixing process, including: Acquire the temperature of the bedrock medium and the flow rate of the target fractured aquifer, and construct the fractured medium heat transfer kinetic equation based on the volume specific heat capacity of the target fractured aquifer, the temperature of the target fractured aquifer, the thermal conductivity coefficient of the target fractured aquifer, the thermal dispersion of the target fractured aquifer, the volume specific heat capacity of the water, the porosity of the target fractured aquifer, the thermal conductivity coefficient of the bedrock medium, the width of the target fractured aquifer, the temperature of the bedrock medium and the flow rate of the target fractured aquifer; The bedrock medium heat transfer kinetic equation is constructed based on the volume specific heat capacity of the bedrock medium, the temperature of the bedrock medium, and the thermal conductivity coefficient of the bedrock medium.

7. The method according to claim 6, characterized in that The determining of initial conditions and boundary conditions based on the influencing parameters of the wellbore thermal mixing process includes: Acquiring initial temperatures in fractures and bedrock media, and constructing the initial conditions based on the temperature of the target fracture aquifer, the temperature of the bedrock medium, and the initial temperatures in the fractures and bedrock media; The boundary conditions are constructed based on the temperature of the target fractured aquifer, the temperature of the bedrock medium, the temperature within the geothermal injection well, and the initial temperatures in the fractures and bedrock medium.

8. The method according to claim 6, characterized in that The determining of the effective thermal diffusion coefficient based on the influencing parameters of the wellbore thermal mixing process comprises: The effective thermal diffusion coefficient is determined based on the thermal conductivity of the target fractured aquifer, the volumetric specific heat capacity of the target fractured aquifer, the thermal dissipation of the target fractured aquifer, the volumetric specific heat capacity of the water, and the flow velocity of the target fractured aquifer.

9. The method according to claim 1, characterized in that: The optimization objective function is constructed based on the analytical solution of the three-stage single well injection and pumping test, and the optimization objective function is used to perform parameter inversion to generate the heat transfer parameter value of the target fractured aquifer, including: Based on the analytical solution of the three-stage single-well injection and pumping test, the optimization objective function is constructed with the goal of minimizing the fitting value of the three-stage single-well injection and pumping test; The optimization objective function is solved to generate heat transfer parameter values ​​of the target fractured aquifer.

10. The method according to claim 9, characterized in that The optimization objective function is constructed based on the analytical solution of the three-stage single well injection and pumping test and with the goal of minimizing the fitting value of the three-stage single well injection and pumping test, including: Determine the simulation value of the sampling point based on the analytical solution of the three-stage single well injection and pumping test; Obtaining the observed value of the sampling point, and determining the mean square error value of the three-stage single well injection and pumping test based on the simulated value of the sampling point and the observed value of the sampling point; The weighting coefficient of the three-stage single-well injection and pumping test is obtained, and the optimization objective function is constructed based on the mean square error value of the three-stage single-well injection and pumping test and the weighting coefficient of the three-stage single-well injection and pumping test.

11. The method according to claim 10, characterized in that The optimization objective function is constructed based on the mean square error value of the three-stage single-well injection and pumping test and the weighted coefficient of the three-stage single-well injection and pumping test. The expression of the optimization objective function is as follows: In the above formula, F represents the optimization objective function, μ i represents the weighting coefficient of the i-th stage, Δf i represents the mean square error value of the i-th stage, and u represents the number of stages in the single-well injection and pumping test.

12. The method according to claim 2, characterized in that: Also includes: The heat transfer parameter value of the target fractured aquifer is compared with the range of the geothermal heat transfer parameter, and when the heat transfer parameter value of the target fractured aquifer meets the range of the geothermal heat transfer parameter, the heat transfer parameter value of the target fractured aquifer is output.

13. A heat transfer parameter inversion device, characterized in that: The device comprises: An acquisition module is used to acquire the target area drilling data and the target area hydrogeological data, and carry out a three-stage single well injection and pumping test based on the target area drilling data and the target area hydrogeological data to determine the influencing parameters of the wellbore thermal mixing process; A construction module, used to construct a mathematical model of a single well injection and pumping test considering the wellbore thermal mixing process based on the influencing parameters of the wellbore thermal mixing process; A solution module, used for solving the mathematical model of the single-well injection and pumping test considering the wellbore thermal mixing process, and generating an analytical solution for the three-stage single-well injection and pumping test; An inversion module is used to construct an optimization objective function based on the analytical solution of the three-stage single-well injection and pumping test, and use the optimization objective function to perform parameter inversion to generate heat transfer parameter values ​​of the target fracture aquifer; wherein the heat transfer parameter values ​​of the target fracture aquifer are used to evaluate geothermal resources.

14. A computer device, characterized in that: include: A memory and a processor, wherein the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the heat transfer parameter inversion method according to any one of claims 1 to 12 by executing the computer instructions.

15. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a computer to execute the heat transfer parameter inversion method according to any one of claims 1 to 12.

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