Methods, apparatus and computer equipment for predicting geothermal conditions in igneous rock distribution areas

Abstract

This specification relates to the field of geophysical research, particularly to methods, apparatus, and computer equipment for predicting geothermal conditions in igneous rock distribution areas. The method includes: constructing an initial three-dimensional geological model of the target area based on lithosphere density and interlayer depth data; iteratively adjusting the structure of the initial three-dimensional geological model based on the correlation between calculated gravity anomaly data from the initial three-dimensional geological model and measured gravity anomaly data from the target area, until the correlation meets a preset threshold range, thus constructing a three-dimensional geological model of the target area; setting the top and bottom temperature boundaries and various thermophysical properties of the three-dimensional geological model; and calculating the subsurface temperature of the target area using three-dimensional thermal field equations to determine the deep geothermal conditions in igneous rock distribution areas. This specification utilizes forward gravity modeling to obtain a three-dimensional geological model, providing accurate structural constraints for subsurface temperature prediction in igneous rock areas, ensuring that the predicted subsurface temperature conforms to the laws of heat conduction.

Description

Technical Field

[0001] This manual pertains to the field of geophysical research, particularly methods, apparatus, and computer equipment for predicting geothermal conditions in igneous rock distribution areas. Background Technology

[0002] Predicting subsurface temperature fields requires understanding the geological structure of the subsurface. Geological modeling, the process of reproducing the structure and composition of the lithosphere, is one of the main aspects of geophysical research. Because the density distribution of matter within the Earth is highly uneven, actual observed gravity values ​​always deviate from theoretically normal gravity values. This variation in gravity, after eliminating various interfering factors, solely due to uneven density distribution, is called gravity anomaly data. As a representation of Earth's density differences, it is often used to reflect the characteristics of subsurface geological bodies.

[0003] Currently, gravity modeling methods are mainly divided into inversion and forward modeling. Inversion modeling interprets the morphology and density of subsurface structures using gravity anomaly field data. Forward modeling adjusts the structure and density of the initial model to fit the model's gravity response to observed gravity.

[0004] In areas where igneous rocks are distributed, complex geological structures limit researchers' understanding of the geothermal field. Igneous rocks, due to their irregular shapes and special thermophysical properties, can exert a significant control over the temperature field. Summary of the Invention

[0005] To address the problem that existing technologies cannot accurately study the temperature field under complex geological structures in igneous rock areas, this specification provides a method, apparatus, and computer equipment for predicting geothermal conditions in igneous rock distribution areas.

[0006] This specification provides an embodiment of a method for predicting geothermal conditions in igneous rock distribution areas. The method includes: constructing an initial three-dimensional geological model of the target area based on lithosphere density and interlayer depth data; iteratively adjusting the structure of the initial three-dimensional geological model based on the correlation between calculated gravity anomaly data of the initial three-dimensional geological model and measured gravity anomaly data of the target area until the correlation meets a preset threshold range, thereby constructing a three-dimensional geological model of the target area; setting the top and bottom temperature boundaries and thermophysical properties of each layer of the three-dimensional geological model; calculating the underground temperature of the target area using a three-dimensional thermal field solving equation; and determining the deep geothermal conditions in the igneous rock distribution area.

[0007] According to one aspect of the embodiments of this specification, the correlation between the calculated gravity anomaly data of the initial three-dimensional geological model and the measured gravity anomaly data of the target area is determined by: acquiring gravity anomaly data of each point in the target area, wherein the gravity anomaly data is the measured gravity anomaly data of the target area obtained in the real world using a gravimeter; determining the calculated gravity anomaly data of the initial three-dimensional geological model based on the gravity anomaly caused by each type of geological body in the target area at the observation point; and calculating the correlation between the calculated gravity anomaly data of the initial three-dimensional geological model and the measured gravity anomaly data of the target area.

[0008] According to one aspect of the embodiments of this specification, iteratively adjusting the structure of the initial three-dimensional geological model based on the correlation between the calculated gravity anomaly data of the initial three-dimensional geological model and the measured gravity anomaly data of the target area includes: when the correlation is less than a preset threshold, adjusting the layer density and layer interface depth in each vertical section of the three-dimensional geological model to obtain a new three-dimensional geological model, wherein multiple vertical sections together constitute the three-dimensional geological model; and recalculating the correlation between the calculated gravity anomaly data of the new three-dimensional geological model and the measured gravity anomaly data of the target area.

[0009] According to one aspect of the embodiments of this specification, constructing an initial three-dimensional geological model of a target area based on lithospheric density and interlayer interface depth data of the target area includes: sampling a first lithospheric layer in the target area to obtain a first lithospheric layer sample; measuring the density of the first lithospheric layer sample to obtain the density of the first lithospheric layer sample; determining the interlayer depth and layer density information of the second lithospheric layer based on seismic and aeromagnetic data of the second lithospheric layer in the target area, wherein the first lithospheric layer and the second lithospheric layer constitute the lithospheric layer of the target area; and constructing an initial three-dimensional geological model of the target area based on the density of the first lithospheric layer sample, the interlayer depth of the second lithospheric layer, and the layer density information of the second lithospheric layer.

[0010] According to one aspect of an embodiment of this specification, the method further includes: performing thermophysical property tests on a first lithosphere sample to obtain the thermophysical properties of the first lithosphere sample; determining the thermophysical properties of a second lithosphere based on the average measured values ​​of samples worldwide, wherein the thermophysical properties of the first lithosphere sample and the thermophysical properties of the second lithosphere constitute the thermophysical properties of the target region.

[0011] According to one aspect of the embodiments of this specification, setting the top and bottom temperature boundaries for the three-dimensional geological model includes: setting the annual average surface temperature of the target area as the upper thermal boundary of the three-dimensional geological model; and setting the Curie isotherm as the lower thermal boundary of the three-dimensional geological model.

[0012] According to one aspect of the embodiments of this specification, the calculation of the underground temperature of the target area using the three-dimensional thermal field equation includes: using the conductive three-dimensional thermal field equation to calculate the three-dimensional temperature distribution.

[0013] This specification also provides an embodiment of a device for predicting geothermal conditions in igneous rock distribution areas. The device includes: a model building unit for constructing an initial three-dimensional geological model of the target area based on the lithosphere density and interlayer depth data of the target area; an iteration unit for iteratively adjusting the structure of the initial three-dimensional geological model based on the correlation between the calculated gravity anomaly data of the initial three-dimensional geological model and the measured gravity anomaly data of the target area, until the correlation meets a preset threshold range, thereby constructing a three-dimensional geological model of the target area; and a geothermal condition determination unit for setting the top and bottom temperature boundaries and thermophysical properties of each layer of the three-dimensional geological model, calculating the underground temperature of the target area using the three-dimensional thermal field solving equation, and determining the deep geothermal conditions of the igneous rock distribution area.

[0014] This specification also provides a computer device, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the method for predicting the geothermal conditions of the igneous rock distribution area.

[0015] This specification also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the method for predicting geothermal conditions in igneous rock distribution areas.

[0016] This manual utilizes sampled measurements and seismic wave velocity inversion to obtain the initial density of various underground geological layers. Combined with regional seismic data, it clarifies the layer boundary depths of the lithosphere. Based on satellite gravity data, it employs a gravity anomaly forward modeling method to obtain a three-dimensional geological model at the lithosphere scale. Then, it sets constraints such as thermophysical properties and temperature boundaries on the three-dimensional model to conduct a three-dimensional steady-state heat conduction simulation, thereby obtaining the spatial distribution of deep-layer temperature. This manual uses forward gravity modeling to obtain a three-dimensional geological model, providing more accurate structural constraints for underground temperature prediction. It avoids the practicality and rationality of temperature prediction results for igneous rock distribution areas due to limitations in the depth and number of data points in traditional geothermal prediction methods, making the predicted underground temperature results more consistent with the heat conduction laws of underground structures. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments or prior art of this specification, the drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this specification. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 The diagram shown is a schematic representation of a method for predicting geothermal conditions in igneous rock distribution areas according to an embodiment of this specification.

[0019] Figure 2 The diagram shown is a flowchart of a method for determining the correlation between an initial three-dimensional geological model and measured gravity anomaly data according to an embodiment of this specification.

[0020] Figure 3 The diagram shown is a flowchart of a method for adjusting an initial three-dimensional geological model according to an embodiment of this specification.

[0021] Figure 4 This is a flowchart illustrating a method for constructing an initial three-dimensional geological model, as described in this specification.

[0022] Figure 5 The diagram shown is a flowchart of a method for determining the thermophysical property parameters of a target region according to an embodiment of this specification.

[0023] Figure 6 The diagram shown is a flowchart of a method for setting temperature boundaries for a three-dimensional geological model according to an embodiment of this specification.

[0024] Figure 7 The diagram shown is a structural schematic of a geothermal condition prediction device for an igneous rock distribution area according to an embodiment of this specification.

[0025] Figure 8 The diagram shown is a schematic representation of the surface geological features of the Pearl River Delta region in South China, according to an embodiment of this specification.

[0026] Figures 9a to 9d The diagram shown is a schematic representation of the interface depth for interpreting geophysical data according to an embodiment of this specification.

[0027] Figure 10 The diagram shown is a schematic diagram of a three-dimensional geological model obtained by forward gravity modeling according to an embodiment of this specification;

[0028] Figures 11a to 11c The diagram shown is a comparison of the calculated gravity anomaly of a three-dimensional geological model and the measured gravity anomaly of the Pearl River Delta in an embodiment of this specification.

[0029] Figures 12a to 12c The figure shown is a cross-sectional schematic diagram of a forward gravity modeling embodiment of this specification;

[0030] Figure 13 The diagram shown is a schematic representation of a three-dimensional temperature simulation result according to an embodiment of this specification.

[0031] Figure 14a This is a temperature distribution characteristic map of the Pearl River Delta region at a depth of 3000 meters, as an embodiment of this specification.

[0032] Figure 14b This is a temperature distribution characteristic map of the Pearl River Delta region at a depth of 5000 meters, as an embodiment of this specification.

[0033] Figure 15 The diagram shown is a structural schematic of a computer device according to an embodiment of this specification.

[0034] Explanation of symbols in the attached drawings:

[0035] 701. Model building unit;

[0036] 702. Iteration unit;

[0037] 703. Geothermal Condition Determination Unit;

[0038] 1502. Computer equipment;

[0039] 1504, Processor;

[0040] 1506. Memory;

[0041] 1508. Drive mechanism;

[0042] 1510. Input / Output Module;

[0043] 1512. Input devices;

[0044] 1514. Output devices;

[0045] 1516. Presentation equipment;

[0046] 1518. Graphical User Interface;

[0047] 1520. Network interface;

[0048] 1522. Communication link;

[0049] 1524. Communication bus. Detailed Implementation

[0050] To enable those skilled in the art to better understand the technical solutions in this specification, the technical solutions in the embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this specification, and not all embodiments. Based on the embodiments in this specification, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this specification.

[0051] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, apparatus, product, or device that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or devices.

[0052] This specification provides the operational steps of the methods described in the embodiments or flowcharts, but based on conventional or non-inventive labor, more or fewer operational steps may be included. The order of steps listed in the embodiments is merely one possible execution order among many and does not represent the only possible execution order. In actual system or device products, the methods shown in the embodiments or drawings can be executed sequentially or in parallel.

[0053] It should be noted that the geothermal condition prediction method for igneous rock distribution areas described in this manual can be used in the field of geophysical research, and this manual does not limit the application fields of the geothermal condition prediction method and device for igneous rock distribution areas.

[0054] Forward gravity modeling is often used to construct three-dimensional geological models of complex structures and magmatic activity areas, thereby obtaining the thickness of the crust and the scale of magmatic rocks.

[0055] Other geophysical data, such as aeromagnetic and seismic data, provide information such as the initial depth of the interface and the initial density of each layer. Before conducting forward gravity modeling, it is necessary to set the initial depth of the model interface and the initial density of each layer.

[0056] Figure 1 The diagram shown is a flowchart of a method for predicting geothermal conditions in an igneous rock distribution area according to an embodiment of this specification, which specifically includes the following steps:

[0057] Step 101: Based on the lithosphere density and interlayer depth data of the target area, construct an initial three-dimensional geological model of the target area.

[0058] This specification focuses on magmatic activity regions with complex geological structures and high levels of geophysical research. It utilizes forward modeling to obtain a three-dimensional geological model at the lithospheric scale. First, an initial three-dimensional geological model of the target region needs to be constructed, including density and interlayer depth information. The lithosphere includes shallow and deep layers. The shallow lithosphere corresponds to surface rocks, and the density of igneous and sedimentary strata can be obtained through sampling and measurement. The deep lithosphere includes, but is not limited to, the upper crust, the low-velocity layer of the middle crust, the lower crust, basaltic intrusions, the lithospheric mantle, and the asthenosphere. The density of the deep lithosphere needs to be obtained through seismic wave velocity inversion. Therefore, in this specification, the shallow lithosphere is referred to as the first lithosphere, and the deep lithosphere as the second lithosphere. Interlayer depth data are obtained from the interpretation of known seismic, aeromagnetic, and other geophysical data. This specification selects a suitable igneous rock distribution area as the target region, using the Pearl River Delta region of South China as a case study. Further details can be found in the references provided. Figure 8 The table shows the surface geological features of the Pearl River Delta region in South China. Before conducting forward gravity modeling, it is necessary to set the initial depth of the model interface and the initial density of each layer. The layer density information is shown in Table 1, and the layer interface depth information is visible. Figures 9a to 9d Table 1 shows the density, thermal conductivity, radioactive heat generation rate, and specific heat capacity of each layer in the three-dimensional geological model.

[0059] Density characteristics of igneous rocks and sedimentary layers can be obtained through surface sampling and measurement. Based on the density characteristics of sedimentary layers, the Pearl River Delta sedimentary layers are divided into low-density sediments and high-density sediments. Density characteristics of the deep lithosphere are derived from seismic data inversion. Depth characteristics of lithospheric interfaces are derived from the interpretation of aeromagnetic and seismic data.

[0060] Step 102: Based on the correlation between the calculated gravity anomaly data of the initial three-dimensional geological model and the measured gravity anomaly data of the target area, iteratively adjust the structure of the initial three-dimensional geological model until the correlation meets a preset threshold range, and construct a three-dimensional geological model of the target area.

[0061] In this step, forward gravity modeling is carried out based on measured gravity anomaly data or measured gravity data obtained in the real world of the target area to obtain a three-dimensional geological model.

[0062] While the initial three-dimensional geological model constructed in step 101 can roughly reflect the geological structure of the target area, it cannot describe the morphology of igneous rocks due to limitations in data resolution and volume properties. Therefore, the initial model lacks practicality and rationality in predicting temperature in igneous rock distribution areas. Consequently, it is necessary to iteratively adjust the structure of the initial three-dimensional geological model, especially the structure of igneous rocks, to reconstruct the measured gravity anomaly. Specifically, the density and depth of the initial three-dimensional geological model are adjusted, and the correlation between the gravity anomaly data of the initial three-dimensional geological model and the measured gravity anomaly data of the target area is recalculated.

[0063] Specifically, by combining the calculated gravity anomaly data of the initial 3D geological model with the measured gravity anomaly data of the target area, the correlation between the calculated gravity anomaly data and the measured gravity anomaly data is calculated. Based on whether the correlation meets preset conditions, the initial 3D geological model is iteratively adjusted. A detailed description of calculating the gravity anomaly data of the initial 3D geological model and determining the correlation between the calculated and measured gravity anomaly data can be found here. Figure 2 .

[0064] Step 103: Set the top and bottom temperature boundaries and thermophysical properties of each layer of the three-dimensional geological model, and use the three-dimensional thermal field to solve the equation to calculate the underground temperature of the target area and determine the deep geothermal conditions of the igneous rock distribution area.

[0065] The thermophysical properties of the target area in the embodiments of this specification can be shown in Table 1, including: thermophysical properties of low-density sediments, high-density sediments, granite intrusions, and deep lithosphere (e.g., upper crust, low-velocity middle crust, lower crust, basaltic intrusions, lithospheric mantle, and asthenosphere). In this step, the thermophysical properties in Table 1 are set as the thermophysical properties of the three-dimensional geological model, and the top and bottom temperature boundaries of the three-dimensional geological model are set. The underground temperature of the target area is calculated using the three-dimensional thermal field solving equation. As can be seen from Table 1, the radiogenic heat generation rate of granite and upper crust is calculated according to an exponentially decreasing law.

[0066] Table 1. Density, thermal conductivity, radioactive heat generation rate, and specific heat capacity of each layer in the three-dimensional geological model.

[0067]

[0068] Note: z in the table represents depth, in km.

[0069] This manual sets constraints such as thermophysical properties and temperature boundaries for the three-dimensional geological model, and performs steady-state temperature simulation based on the three-dimensional thermal field solution equation to obtain the spatial distribution of deep temperature.

[0070] This manual utilizes forward gravity modeling to obtain a three-dimensional geological model, providing more accurate structural constraints for predicting underground temperature in igneous rock areas. It avoids the lack of practicality and rationality in temperature prediction results for igneous rock distribution areas due to the limitations of data point depth and quantity in traditional geothermal prediction methods, making the predicted underground temperature results more consistent with the heat conduction laws of underground structures.

[0071] Figure 2 The diagram shown is a flowchart of a method for determining the correlation between an initial three-dimensional geological model and measured gravity anomaly data according to an embodiment of this specification. The method specifically includes the following steps:

[0072] Step 201: Obtain gravity anomaly data at each point in the target area. The gravity anomaly data is the measured gravity anomaly data of the target area obtained in the real world using a gravimeter.

[0073] In gravity exploration, due to the highly uneven distribution of material density within the Earth's interior, the actual observed gravity values ​​always deviate from the theoretically normal gravity values. This variation in gravity, after eliminating various interfering factors, and solely caused by the uneven distribution of material density, is called a gravity anomaly. Gravity anomaly data, as a representation of differences in Earth's density, can be used to reflect the characteristics of underground geological bodies. In practice, gravimeters can be used to detect gravity anomalies at specific locations.

[0074] Step 202: Determine the calculated gravity anomaly data of the initial three-dimensional geological model based on the gravity anomaly caused by each type of geological body at the observation point in the target area.

[0075] In the embodiments of this specification, the range of the three-dimensional geological model from the surface to the deep strata includes various geological bodies. Therefore, by calculating the gravity anomaly caused by each type of geological body in the target area at the observation point, the calculated gravity anomaly data of the initial three-dimensional geological model is determined.

[0076] In this step, as described in the embodiments of this specification, the target area extends from the surface to deep strata and includes various geological bodies. It is necessary to calculate the gravity anomaly caused by each type of geological body at the observation point within the target area. The formula for calculating the gravity anomaly of any shape within the target area is as follows:

[0077]

[0078] In the formula: Δg represents the gravity anomaly, G represents the gravitational constant; (x,y,z) represents the coordinates of the observation point; V represents the volume of the geological body, m 3 ρ represents the residual density of the geological body, kg / m³ 3(ξ,η,ζ) represents the coordinates of the remaining mass element Δm=ρdξdηdζ, where x, y, z represent the three-dimensional coordinates in the three-dimensional coordinate system.

[0079] Step 203: Calculate the correlation between the calculated gravity anomaly data of the initial three-dimensional geological model and the measured gravity anomaly data of the target area.

[0080] In this step, the coefficient of determination R is used. 2 Evaluate whether the initial 3D geological model can accurately represent the actual geological conditions of the target area. R 2 R is an indicator used to assess the degree of agreement between predicted and actual values ​​in a regression model. 2 This study investigates the linear correlation between two variables: gravity anomaly data and measured gravity anomaly data. This correlation reflects the degree of fit between the three-dimensional geological model and the actual geological conditions. R0 2 The value range is between 0 and 1. A correlation close to 1 indicates a good model fit, while a correlation close to 0 indicates a poor model fit. Specifically, the coefficient of determination R... 2 The calculation formula is as follows:

[0081] Among them, R 2 x represents the coefficient of determination. i This represents the measured gravity anomaly data at the i-th point in the target region. y represents the average value of measured gravity anomaly data in the target area. i This represents the calculated gravity anomaly data at the i-th point in the three-dimensional geological model. This represents the average value of the calculated gravity anomaly data of the three-dimensional geological model, where n represents the total number of points in the target area.

[0082] In the embodiments of this specification, each time the three-dimensional geological model is adjusted, the correlation between the calculated gravity anomaly data and the measured gravity anomaly data of the three-dimensional geological model needs to be recalculated.

[0083] Figure 3 The diagram shown is a flowchart of a method for adjusting an initial three-dimensional geological model according to an embodiment of this specification, which specifically includes the following steps:

[0084] Step 301: When the correlation is less than a preset threshold, adjust the layer density and layer interface depth in each vertical section of the initial three-dimensional geological model to obtain a new three-dimensional geological model. Multiple vertical sections together constitute the three-dimensional geological model.

[0085] In this step, the coefficient of determination R 2 The preset threshold can be set to 0.9. If R 2If the value is less than the preset threshold, it indicates that the 3D geological model does not match the measured conditions of the target area sufficiently. In other words, the 3D geological model cannot accurately reflect the geological structure of the actual target area. Therefore, iterative adjustments to the 3D geological model are needed until a 3D geological model that accurately reflects the geological structure of the actual target area is obtained. The 3D geological model consists of multiple vertical sections, such as... Figure 10 As shown, each vertical section consists of a layer boundary and the geological layers between the boundaries. Connecting the layer boundaries of adjacent sections forms a geological body with a three-dimensional structure. By adjusting the number and position of structural points on the layer boundaries, the shape of the layer boundaries can be changed, thereby altering the shape of the three-dimensional structure of the geological body. This allows for the overall adjustment of the three-dimensional geological model, resulting in a new three-dimensional geological model.

[0086] In this step, the depth of the granite structure in each vertical section of the initial 3D geological model is adjusted to achieve an overall adjustment of the initial 3D geological model, thereby obtaining a new 3D geological model. Specifically, the depth of each point in the granite intrusion region of each vertical section is adjusted, including but not limited to: adding points in the granite intrusion region, deleting points, and changing the depth position of existing points, etc., to adjust the density and depth of the granite in the vertical section, thereby achieving an overall adjustment of the initial 3D geological model.

[0087] Step 302: Recalculate the correlation between the calculated gravity anomaly data of the new three-dimensional geological model and the measured gravity anomaly data of the target area.

[0088] In this step, following the correlation calculation method described above, the predicted gravity anomaly data of the new three-dimensional geological model is recalculated, and the correlation between the predicted gravity anomaly data of the new three-dimensional geological model and the measured gravity anomaly data of the target area is further calculated. Steps 301 and 302 are repeated until the coefficient of determination R is reached. 2 Greater than 0.99. This manual describes forward gravity modeling based on satellite gravity data, and the resulting initial three-dimensional geological model reconstructs the observed gravity anomalies.

[0089] Figure 4 This document presents a flowchart of a method for constructing an initial three-dimensional geological model, which includes the following steps:

[0090] Step 401: Sample the first lithosphere of the target area to obtain first lithosphere samples. The first lithosphere refers to surface rocks, specifically including igneous and sedimentary rocks. In this specification, the first lithosphere and surface rocks can be understood as shallow strata, including surface and well-drilled sedimentary strata. Sampling of the surface rocks yields samples of both igneous and sedimentary rocks.

[0091] Step 402: Measure the density of the first lithosphere sample to obtain the density of the first lithosphere sample. Specifically, the density of the first lithosphere sample includes the density information of surface igneous rocks and the density information of sedimentary rocks.

[0092] This specification describes a study conducted in the Pearl River Delta region of South China. Surface rocks were collected from the target area, and their densities were determined, specifically including the densities of igneous and sedimentary rocks. Based on extensive surface sampling and measurements, strata with similar densities were further grouped. The sedimentary layers in the Pearl River Delta region are mainly divided into two groups: one group consists of relatively low-consolidation clastic rocks from the Cretaceous period onwards, and the other group consists of hard, high-density metamorphic sandstone, limestone, shale, and sandstone from the Sinian to Jurassic shallow marine periods.

[0093] In this specification, the sedimentary strata of the Pearl River Delta can be roughly divided into low-density sediments and high-density sediments based on their lithology, density, and thermophysical properties.

[0094] Step 403: Based on the seismic and aeromagnetic data of the second lithospheric layer in the target area, determine the interface depth and layer density information of the second lithospheric layer. The first and second lithospheric layers constitute the lithospheric layers of the target area. The interfaces of the second lithospheric layer include the sedimentary floor, the upper crustal floor, the Moho discontinuity, and the lithospheric floor. The density layers of the second lithospheric layer include the densities of the upper crust, the low-velocity layer of the middle crust, the lower crust, the lithospheric mantle, and the asthenosphere.

[0095] Based on geophysical research findings including seismic and aeromagnetic data, the depths of the main interfaces of the second lithospheric layer in the target area were determined. These main interfaces include, but are not limited to: the sedimentary floor, the upper crustal floor, the Moho discontinuity, and the lithospheric floor. Density information for the deep lithospheric layers was obtained from a seismic velocity inversion profile density model of the region, and the density range was determined based on the depth range. The main density layers in the deep region include: the upper crust, the low-velocity layer of the middle crust, the lower crust, the lithospheric mantle, and the asthenosphere.

[0096] In this instruction manual, such as Figures 9a to 9d The diagram illustrates the depth of the lithospheric interface in the Pearl River Delta as interpreted from geophysical data in embodiments of this specification. Aeromagnetic data analysis reveals the depth of the top surface of the magnetic basement of the Pearl River Delta, reflecting the depth distribution characteristics of the major basins. Figure 9a The depth of the top surface of the magnetic basement is interpreted from aeromagnetic data. Furthermore, through function simulations and artificial seismic exploration results, the depth characteristics of the top surface of the low-velocity layer in the middle crust, the Moho discontinuity, and the bottom boundary of the lithosphere in the Pearl River Delta can be determined. Figure 9b For the depth of the top surface of the low-velocity layer in the middle crust, Figure 9c For the depth of the Mohorovičić discontinuity, Figure 9dThis represents the depth of the lithosphere's lower boundary. Layer density information is shown in Table 1. This specification integrates an initial three-dimensional geological model based on the depth of the main interfaces and the layer density information between interfaces.

[0097] Step 404: Based on the density of the first lithosphere sample, the interface depth of the second lithosphere, and the layer density information of the second lithosphere, construct an initial three-dimensional geological model of the target area. For example... Figure 10 The diagram shows a schematic representation of the three-dimensional geological model of the Pearl River Delta obtained through forward gravity modeling, as described in this specification. At the start of modeling, the target area is expanded outwards by 100 km to minimize gravity edge effects. The simulated target area measures 361 km east-west and 332 km north-south. The initial vertical depth of the three-dimensional geological model is set to 100 km to include all interfaces that generate density contrasts, extending from the surface to the base of the lithosphere.

[0098] Furthermore, the initial three-dimensional geological model was constructed from 42 vertical sections (such as...). Figure 10 (As shown). Specifically, structural points on the same layer boundary of adjacent sections are connected to form a three-dimensional geological body with a triangular polyhedral structure. In regions where the triangular polyhedrons have approximately constant density, density differences between polyhedra will generate calculated gravity anomalies. In the embodiments of this specification, the vertical sections are oriented north-south, and the distance between adjacent interfaces is approximately 8.7 km. To fit the high gravity anomaly in the region, and considering the Cenozoic lithospheric activity characteristics of the Pearl River Delta, a high-density mantle-derived basaltic intrusion was established in the lower crust.

[0099] Figures 11a to 11c The diagram shown is a comparison of observed gravity and the final model's gravity response according to an embodiment of this specification. The final model of forward gravity modeling reproduces the observed gravity (…). Figure 11a , Figure 11b The standard deviation of the difference between the measured gravity anomaly data and the calculated gravity anomaly data from the model is 1.36 mGal. Figure 11c The coefficient of determination between the measured gravity anomaly data and the calculated gravity anomaly data is 0.994, which is higher than the set threshold, indicating that an acceptable fit has been achieved.

[0100] like Figures 12a to 12c The figure shows a schematic diagram of a vertical cross-section of a forward gravity modeling embodiment of this specification. In the figure, the black dashed line in the crustal model represents the depth of the top surface of the magnetic basement interpreted from aeromagnetic data, the long white dashed line represents the depth of the top surface of the low-velocity layer in the middle crust interpreted from seismic data, and the short white dashed line represents the depth of the Moho discontinuity interpreted from seismic data. Figures 12a to 12cA schematic diagram of three vertical sections from the model is shown, illustrating the crustal structure features of the initial 3D geological model. The calculated gravity anomaly data generated by the geological structures shown in the sections almost perfectly matches the measured gravity anomaly data, indicating that the geological model can reflect the actual geological structure. The forward gravity modeling method can effectively obtain the subsurface geological structure, especially the structure of igneous rocks. Larger-scale granite intrusions exist beneath the Pearl River Delta. The shallow structure of the geological model matches the topography, with higher-altitude mountainous areas corresponding to the regions where granite intrusions are located, while plains correspond to sedimentary basins.

[0101] In this step, the interface structures interpreted from the aforementioned geophysical data lack structural features of igneous intrusive bodies such as granites in the Earth's crust. Forward gravity modeling methods focus on constructing the morphology of these intrusive bodies.

[0102] Figure 5 The diagram shown is a flowchart of a method for determining the thermophysical property parameters of a target region according to an embodiment of this specification, which specifically includes the following steps:

[0103] Step 501: Perform thermophysical property testing on the first lithosphere sample to obtain the thermophysical properties of the first lithosphere sample. In the embodiments of this specification, the first lithosphere includes igneous rocks and sedimentary rocks. Perform thermophysical property testing on samples collected from the Earth's surface to obtain the thermophysical properties of shallow crustal igneous rocks and sedimentary rocks, respectively.

[0104] Step 502: Determine the thermophysical properties of the second lithospheric sample based on the average measured values ​​of global samples. The thermophysical properties of the first and second lithospheric samples constitute the thermophysical properties of the target region. In this specification, the thermophysical properties of the second lithospheric sample are obtained with reference to the average measured values ​​of global samples. Thus, the thermophysical properties of the shallow crust and deep lithospheric layers are determined, thereby obtaining the thermophysical properties of the entire target region.

[0105] Under the constraints of a suitable three-dimensional geological model, by setting thermophysical properties and temperature boundaries, and using the three-dimensional thermal field to solve equations to calculate the three-dimensional temperature distribution, the deep geothermal conditions in igneous rock distribution areas can be predicted more accurately, providing a scientific basis that is more in line with the regional geological characteristics for the exploration and development of geothermal resources in the region.

[0106] Figure 6 The diagram shown is a flowchart of a method for setting temperature boundaries for a three-dimensional geological model according to an embodiment of this specification, which specifically includes the following steps:

[0107] Step 601: Set the annual average surface temperature of the target area as the upper thermal boundary of the three-dimensional geological model.

[0108] In the embodiments described in this specification, it is assumed that the temperature gradient on the thermal lateral boundary is zero, and the lateral boundary is closed for heat transfer. This means that only the upward transfer of heat is considered within the three-dimensional geological model, and there is no energy exchange between the model and areas outside the model in the lateral direction. Based on this, the annual average surface temperature of the Pearl River Delta region (22.5℃) is set as the upper thermal boundary of the three-dimensional geological model.

[0109] Step 602: Set the Curie isotherm as the lower thermal boundary of the three-dimensional geological model.

[0110] In this specification, magnetite is the most abundant mineral in the Earth's crust, and its demagnetization temperature is 580°C. Therefore, the Curie isotherm temperature is set to 580°C. When the temperature of a stratum exceeds the Curie temperature, the stratum loses its magnetism. Aeromagnetic data reflects the magnetic characteristics of strata above the Curie isotherm depth; therefore, aeromagnetic data can be used to interpret the depth of the Curie isotherm in a region. In this specification, the Curie isotherm is set as the lower thermal boundary of the three-dimensional geological model, such as... Figure 13 As shown. Figure 13 The figure shows a schematic diagram of the three-dimensional temperature simulation results. In the figure, the annual average surface temperature of the target area is set as the upper thermal boundary of the three-dimensional geological model, and the Curie isotherm is set as the lower thermal boundary of the three-dimensional geological model.

[0111] In the embodiments of this specification, the temperature simulation of the three-dimensional geological model needs to consider both transient and steady-state conditions. Transient conditions refer to the presence of unstable heat sources or active media within the geological body, such as magma chambers and fluid activity, which prevent the underground temperature from remaining constant. Steady-state conditions only consider the constant underground temperature state, where the temperature distribution is mainly related to the geological body's structure and thermophysical properties, with heat sources originating from deep mantle heating and radioactive heat generation within the geological body.

[0112] By combining the thermophysical properties of the three-dimensional geological model, the temperature of the three-dimensional geological model is determined by solving the thermal equations of the three-dimensional thermal field:

[0113] Where ρ represents density, kg / m³ 3 C P represents specific heat capacity, J / (kg·K); T represents temperature; k represents thermal conductivity, W / (m·K); The temperature gradient is represented by K / m; t represents time by s; and Q represents the rate of radioactive heat generation by μW / m. 3 ; This indicates the change in temperature over time. This represents a three-dimensional operator that gives the spatial variation of temperature.

[0114] Under steady-state thermal conditions, the model's temperature does not change over time; the model is only sensitive to thermal conductivity, radioactive heat generation rate, and thermal boundary conditions. Under transient conditions, the model's temperature changes with variations in thermal conductivity, radioactive heat generation rate, and thermal boundary conditions. Therefore, the simulated thermal conductivity field of the target region can be determined using the above method. Furthermore, the deep geothermal conditions of igneous rocks can be determined based on the simulated thermal conductivity field. Specifically, the deep geothermal conditions are clarified by extracting temperature maps from different depths and cross-sections.

[0115] It can be determined that the temperature distribution characteristics at depths of 3000 meters and 5000 meters underground in the Pearl River Delta region are as follows: Figure 14a and Figure 14b As shown. Figure 14a This is a temperature distribution characteristic map of the Pearl River Delta region at a depth of 3000 meters, as an embodiment of this specification. Figure 14b This is a temperature distribution characteristic map of the Pearl River Delta region at a depth of 5000 meters, as an embodiment of this specification. Figure 14a At a depth of 3000 meters, the temperature can reach up to 120℃; while... Figure 14b At a depth of 5000 meters, the temperature ranges from 120℃ to 175℃. High-temperature zones are mainly located in the Sanshui Basin, Xinhui Basin, and Yunkai area. This specification utilizes forward gravity modeling to obtain a three-dimensional geological model, providing more accurate structural constraints for underground temperature prediction. This avoids the limitations of traditional geothermal prediction methods, which suffer from limitations in data point depth and quantity, leading to impracticality and rationality in temperature predictions for magmatic rock distribution areas. The predicted underground temperature results are thus more consistent with the heat conduction patterns of underground structures.

[0116] like Figure 7 The diagram shown is a structural schematic of a geothermal condition prediction device for igneous rock distribution areas according to an embodiment of this specification. The basic structure of the device is illustrated in this diagram. The functional units and modules can be implemented using software, or they can be implemented using general-purpose chips or specific chips to predict the geothermal conditions in igneous rock distribution areas. The device specifically includes:

[0117] Model building unit 701 is used to build an initial three-dimensional geological model of the target area based on the density and interlayer depth data of the lithosphere in the target area.

[0118] The iteration unit 702 is used to iteratively adjust the structure of the initial three-dimensional geological model based on the correlation between the calculated anomaly data of the initial three-dimensional geological model and the measured gravity anomaly data of the target area, until the correlation meets a preset threshold range, thereby constructing a three-dimensional geological model of the target area.

[0119] The geothermal condition determination unit 703 is used to set the top and bottom temperature boundaries and the thermophysical properties of each layer of the three-dimensional geological model, calculate the underground temperature of the target area using the three-dimensional thermal field solving equation, and determine the deep geothermal condition of the igneous rock distribution area.

[0120] This manual utilizes forward gravity modeling to obtain a three-dimensional geological model, providing more accurate structural constraints for predicting underground temperature in igneous rock areas. It avoids the lack of practicality and rationality in temperature prediction results for igneous rock distribution areas due to the limitations of data point depth and quantity in traditional geothermal prediction methods, making the predicted underground temperature results more consistent with the heat conduction laws of underground structures.

[0121] like Figure 15 The diagram illustrates a computer device provided in an embodiment of this specification. The geothermal condition prediction method for igneous rock distribution areas described in this application can be applied to this computer device. The computer device 1502 may include one or more processors 1504, such as one or more central processing units (CPUs), each of which can implement one or more hardware threads. The computer device 1502 may also include any memory 1506 for storing any kind of information, such as code, settings, data, etc. Non-limitingly, for example, the memory 1506 may include any type of RAM, any type of ROM, flash memory, hard disk, optical disk, etc. More generally, any memory can use any technology to store information. Further, any memory can provide volatile or non-volatile retention of information. Further, any memory can represent a fixed or removable component of the computer device 1502. In one case, when the processor 1504 executes associated instructions stored in any memory or combination of memories, the computer device 1502 can perform any operation of the associated instructions. The computer device 1502 also includes one or more drive mechanisms 1508 for interacting with any memory, such as a hard disk drive mechanism, an optical disk drive mechanism, etc.

[0122] Computer device 1502 may also include an input / output module 1510 (I / O) for receiving various inputs (via input device 1512) and providing various outputs (via output device 1514). A specific output mechanism may include a presentation device 1516 and an associated graphical user interface (GUI) 1518. In other embodiments, the input / output module 1510 (I / O), input device 1512, and output device 1514 may be omitted, and the device may function solely as a computer device within a network. Computer device 1502 may also include one or more network interfaces 1520 for exchanging data with other devices via one or more communication links 1522. One or more communication buses 1524 couple the components described above together.

[0123] Communication link 1522 can be implemented in any way, such as via a local area network, a wide area network (e.g., the Internet), a point-to-point connection, or any combination thereof. Communication link 1522 may include any combination of hardwired links, wireless links, routers, gateway functions, name servers, etc., governed by any protocol or combination of protocols.

[0124] Corresponding to Figures 1 to 6 In addition to the methods described above, embodiments of this specification also provide a computer-readable storage medium storing a computer program that, when executed by a processor, performs the steps of the methods described above.

[0125] This specification also provides computer-readable instructions, wherein when a processor executes the instructions, the program therein causes the processor to perform the following... Figures 1 to 6 The method shown.

[0126] It should be understood that in the various embodiments of this specification, the sequence number of each process does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this specification.

[0127] It should also be understood that, in the embodiments of this specification, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this specification generally indicates that the preceding and following related objects have an "or" relationship.

[0128] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed in this specification can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of each example have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this specification.

[0129] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0130] In the several embodiments provided in this specification, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the couplings or direct couplings or communication connections shown or discussed may be indirect couplings or communication connections through some interfaces, devices, or units, or they may be electrical, mechanical, or other forms of connection.

[0131] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of the embodiments described in this specification, depending on actual needs.

[0132] Furthermore, the functional units in the various embodiments of this specification can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0133] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this specification, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this specification. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0134] This specification uses specific embodiments to illustrate the principles and implementation methods of this specification. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this specification. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this specification. Therefore, the content of this specification should not be construed as a limitation of this specification.

Claims

1. A method for predicting geothermal conditions in igneous rock distribution areas, characterized in that, The method includes: Based on the lithospheric density and interlayer depth data of the target area, an initial three-dimensional geological model of the target area is constructed, including: sampling the first lithospheric layer of the target area to obtain a first lithospheric layer sample; measuring the density of the first lithospheric layer sample to obtain its density; determining the interlayer depth and layer density information of the second lithospheric layer based on seismic and aeromagnetic data of the target area; the first and second lithospheric layers constitute the lithospheric layers of the target area; and constructing the initial three-dimensional geological model of the target area based on the density of the first lithospheric layer sample, the interlayer depth of the second lithospheric layer, and the layer density information of the second lithospheric layer. Based on the correlation between the calculated gravity anomaly data of the initial three-dimensional geological model and the measured gravity anomaly data of the target area, the structure of the initial three-dimensional geological model is iteratively adjusted, including: when the correlation is less than a preset threshold, adjusting the layer density and layer interface depth in each vertical section of the initial three-dimensional geological model to obtain a new three-dimensional geological model, wherein multiple vertical sections together constitute the three-dimensional geological model; recalculating the correlation between the calculated gravity anomaly data of the new three-dimensional geological model and the measured gravity anomaly data of the target area until the correlation meets the preset threshold range, thereby constructing a three-dimensional geological model of the target area; The top and bottom temperature boundaries and thermophysical properties of each layer of the three-dimensional geological model are set, and the underground temperature of the target area is calculated by solving the equations of the three-dimensional thermal field to determine the deep geothermal conditions of the igneous rock distribution area.

2. The method for predicting geothermal conditions in igneous rock distribution areas according to claim 1, characterized in that, The correlation between the calculated gravity anomaly data of the initial 3D geological model and the measured gravity anomaly data of the target area was determined using the following method: Acquire gravity anomaly data at various points in the target area, wherein the gravity anomaly data is measured gravity anomaly data of the target area in the real world using a gravimeter device; Based on the gravity anomalies caused by each type of geological body at the observation point in the target area, the calculated gravity anomaly data of the initial three-dimensional geological model are determined; The correlation between the calculated gravity anomaly data of the initial three-dimensional geological model and the measured gravity anomaly data of the target area was calculated.

3. The method for predicting geothermal conditions in igneous rock distribution areas according to claim 1, characterized in that, The method further includes: The thermophysical properties of the first lithosphere sample were tested to obtain the thermophysical properties of the first lithosphere sample; The thermophysical properties of the second lithosphere are determined based on the average measured values ​​of global samples. The thermophysical properties of the first lithosphere sample and the thermophysical properties of the second lithosphere constitute the thermophysical properties of the target region.

4. The method for predicting geothermal conditions in igneous rock distribution areas according to claim 1, characterized in that, Setting the top and bottom temperature boundaries for the three-dimensional geological model includes: The annual average surface temperature of the target area is set as the upper thermal boundary of the three-dimensional geological model; The Curie isotherm is set as the lower thermal boundary of the three-dimensional geological model.

5. The method for predicting geothermal conditions in igneous rock distribution areas according to claim 4, characterized in that, The calculation of the underground temperature of the target area using the three-dimensional thermal field equations includes: using the conduction three-dimensional thermal field equations to calculate the three-dimensional temperature distribution.

6. A device for predicting geothermal conditions in igneous rock distribution areas, characterized in that, The device includes: The model building unit is used to construct an initial three-dimensional geological model of the target area based on the lithospheric density and interlayer depth data of the target area. This includes: sampling the first lithospheric layer of the target area to obtain a first lithospheric layer sample; measuring the density of the first lithospheric layer sample to obtain its density; determining the interlayer depth and layer density information of the second lithospheric layer based on seismic and aeromagnetic data of the target area; the first and second lithospheric layers constituting the lithospheric layers of the target area; and constructing the initial three-dimensional geological model of the target area based on the density of the first lithospheric layer sample, the interlayer depth of the second lithospheric layer, and the layer density information of the second lithospheric layer. An iterative unit is used to iteratively adjust the structure of the initial three-dimensional geological model based on the correlation between the calculated gravity anomaly data of the initial three-dimensional geological model and the measured gravity anomaly data of the target area. This includes: when the correlation is less than a preset threshold, adjusting the layer density and layer interface depth in each vertical section of the initial three-dimensional geological model to obtain a new three-dimensional geological model, wherein multiple vertical sections together constitute the three-dimensional geological model; recalculating the correlation between the calculated gravity anomaly data of the new three-dimensional geological model and the measured gravity anomaly data of the target area until the correlation meets a preset threshold range, thereby constructing a three-dimensional geological model of the target area. The geothermal condition determination unit is used to set the top and bottom temperature boundaries and the thermophysical properties of each layer of the three-dimensional geological model, calculate the underground temperature of the target area using the three-dimensional thermal field solving equation, and determine the deep geothermal condition of the igneous rock distribution area.

7. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the method according to any one of claims 1 to 5.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the method according to any one of claims 1 to 5.

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