Methods for quantifying the relationship between altered and crystalline crustal heterogeneity and thermal anomalies

Abstract

This invention discloses a method for quantifying the relationship between the heterogeneity of altered crystalline crust and thermal anomalies. The method includes constructing a geological model of the heterogeneous crystalline crust, where different alteration layers are marked; defining and setting the thermal properties of the different alteration layers to obtain heterogeneity parameters; classifying the degree of alteration into several levels based on the geological characteristics of the alteration layers to obtain alteration degree parameters; establishing a quantitative relationship between alteration degree and thermal properties parameters, and obtaining thermal conductivity variation curves for different altered rocks through experiments; constructing a thermal conduction model based on the Fourier heat conduction equation, and introducing the heterogeneity and alteration degree parameters into the thermal conduction model to dynamically adjust the thermal conductivity of each alteration region. By introducing a heterogeneous crust model and alteration degree parameters, the accuracy of calculating the relationship between crustal thickness heterogeneity and surface thermal anomalies is significantly improved.

Description

Technical Field

[0001] This invention relates to the field of geology, specifically to a method for quantifying the relationship between the heterogeneity of altered and crystalline crust and thermal anomalies. Background Technology

[0002] The deformation process of the crystalline crust leads to uneven crustal thickness, becoming a major driving force in shaping the passive continental margin morphology and a key controlling factor in earthquake prediction and hydrocarbon reservoir distribution. Surface thermal anomalies, as directly observable geophysical data, provide an important window for studying the movement of matter and energy transfer within the Earth. Revealing the relationship between uneven crystalline crustal thickness and thermal anomalies can deepen our understanding of crustal dynamics and provide more accurate models for earthquake prediction and hydrocarbon resource exploration, thereby helping to elucidate the intrinsic link between crustal evolution and resource distribution.

[0003] Currently, most research methods on the relationship between uneven crystalline crust thickness and thermal anomalies assume that the crystalline crust is homogeneous sialic rock, and perform heat conduction equations or thermal inversion calculations based on this assumption. However, with the deepening of continental margin drilling and integrated geophysical exploration, scientists have discovered in recent years that the lithosphere often enters an over-extension state during extension. At this time, the crust may undergo high-temperature alteration and magma contamination, and even widespread alteration of serpentinized mantle emplacement. Therefore, continuing to use a homogeneous sialic crust model may lead to significant errors in the quantitative relationship between uneven crystalline crust thickness and thermal anomalies, resulting in inaccurate understandings. This will directly affect the in-depth understanding of crustal evolution and resource distribution, as well as the construction of earthquake prediction and oil and gas resource exploration models. Summary of the Invention

[0004] To address the challenge of assessing the relationship between the heterogeneity of crystalline crust thickness and thermal anomalies in the evaluation of alteration effects during lithosphere overextension, this invention provides a method for quantifying the relationship between the heterogeneity of altered crystalline crust and thermal anomaly values. This method, considering the degree of alteration and further constrained by crustal heterogeneity, constructs a more refined heat conduction model that reflects the true overextension environment, thereby achieving accurate quantification of the relationship between the heterogeneity of altered crust thickness and thermal anomalies.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] Compared with the prior art, the advantages of this invention are as follows:

[0007] A method for quantifying the relationship between the heterogeneity of altered and crystalline crust and thermal anomalies includes:

[0008] A geological model of a heterogeneous crystalline crust is constructed, wherein different alteration layers are marked in the geological model of the heterogeneous crystalline crust;

[0009] The thermal properties of the different alteration layers are defined and set to obtain the heterogeneous parameters;

[0010] Based on the geological characteristics of the altered layer, the degree of alteration is divided into several levels, and the degree of alteration parameters are obtained.

[0011] A quantitative relationship between alteration degree and thermophysical parameters was established, and the thermal conductivity variation curves of different altered rocks were obtained through experiments.

[0012] A heat conduction model is constructed based on the Fourier heat conduction equation. The heterogeneity and alteration degree parameters are introduced into the heat conduction model to dynamically adjust the thermal conductivity of each altered region. The established quantitative relationship between alteration degree and thermophysical parameters, as well as the thermal conductivity variation curves of different altered rocks, are used as the main control parameters and applied to the Fourier heat conduction equation. The Fourier heat conduction equation is then discretized to obtain an improved heat conduction model, thereby quantifying the relationship between the heterogeneity of altered crust thickness and thermal anomalies.

[0013] Optionally, the method for quantifying the relationship between altered and crystalline crustal heterogeneity and thermal anomaly values ​​is characterized by further comprising:

[0014] Using the improved heat conduction model, the heat flux density at the surface and at various depths was calculated. By comparing the measured surface thermal anomaly data, the thermal anomaly values ​​at the surface and at various depths were obtained.

[0015] Analyze the thermal anomaly data of the altered area, adjust the contribution of the alteration degree parameter to the thermal anomaly, and use this to correct the obtained thermal anomaly values ​​of the surface and each depth layer, and obtain the thermal anomaly value correction calculation results.

[0016] The accuracy of the improved heat conduction model and the calculation results of the corrected thermal anomaly values ​​were verified by comparing them with the measured surface thermal anomalies and crustal thickness heterogeneity.

[0017] Optionally, a geological model of a heterogeneous crystalline crust can be constructed using the following methods:

[0018] To acquire and analyze geophysical exploration data from continental margin regions in order to obtain the physical changes and alteration degree of the lithosphere in the ultra-extensional region;

[0019] Based on refraction seismic data, crustal heterogeneity is divided into multiple layers or units, resulting in super-extensional units.

[0020] Different alteration levels were added to the super-extensional units, and corresponding lithological changes were marked to complete the geological model construction of the heterogeneous crystalline crust.

[0021] Optionally, the analysis includes crustal thickness, crustal deformation characteristics, distribution of serpentinized mantle emplacements, seismic facies, lithofacies identification, and statistical analysis.

[0022] Optionally, the geophysical exploration data includes drilling and seismic profile data.

[0023] Optionally, the Fourier heat conduction equation is: Where q is heat flux, k is thermal conductivity, and T is temperature gradient.

[0024] Optionally, the heat conduction equation can be discretized using the finite element method or the finite difference method, and the changes in crustal heat flow with depth and time can be calculated layer by layer.

[0025] Optionally, the thermal properties of different alteration layers can be defined and set based on thermal conductivity, density, and specific heat capacity.

[0026] Optionally, the heterogeneous parameters include changes in thermophysical properties resulting from longitudinal heterogeneous lithology and mineral phase variations.

[0027] Optionally, experimental and statistical methods can be used to establish a quantitative relationship between alteration degree and thermophysical parameters.

[0028] Compared with the prior art, the advantages of this invention are as follows:

[0029] To address the errors inherent in traditional homogeneous silica-alumina crustal models during alteration analysis, the introduction of heterogeneous crustal models and alteration degree parameters significantly improves the accuracy of calculating the relationship between crustal thickness heterogeneity and surface thermal anomalies. By revealing the relationship between crystalline crustal thickness heterogeneity and thermal anomalies, this study deepens our understanding of crustal dynamics, particularly the evolution and thermodynamic behavior of the crust in an overextended state. It enables precise quantification of the interrelationship between crustal thickness and thermal anomalies, improving the accuracy of earthquake prediction and oil and gas resource distribution models, and providing more accurate scientific evidence for risk assessment and resource development in related fields. Attached Figure Description

[0030] Figure 1 A flowchart illustrating the implementation of a method for quantifying the relationship between the heterogeneity of altered and crystalline crust and thermal anomalies, as provided in this application embodiment;

[0031] Figure 2 A flowchart illustrating the implementation of a method for quantifying the relationship between the heterogeneity of altered and crystalline crust and thermal anomalies, provided as a preferred embodiment of this application.

[0032] Figure 3 A flowchart illustrating the construction process of a geological model for a heterogeneous crystalline crust;

[0033] Figure 4 Thinning feature map of a certain estuary basin and a certain sea basin area;

[0034] Figure 5 Assign different alteration degree maps to a certain estuary basin and a certain sea basin area;

[0035] Figure 6 Calculate heat flux density maps for a model of a river estuary basin and a sea basin area;

[0036] Figure 7 This is a map showing the distribution of the parameter λ, which relates the heterogeneity of altered and crystalline crust and thermal anomalies in a certain river estuary basin and a certain sea basin area. Detailed Implementation

[0037] Example:

[0038] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0039] See Figure 1 As shown in the figure, the method for quantifying the relationship between the heterogeneity of altered and crystalline crust and thermal anomaly values ​​provided in this embodiment mainly includes the following steps:

[0040] 110. Construct a geological model of a heterogeneous crystalline crust, wherein the geological model of the heterogeneous crystalline crust marks different alteration layers;

[0041] 120. Define and set the thermal properties of the different alteration layers to obtain the heterogeneity parameters;

[0042] 130. Based on the geological characteristics of the altered layer, the degree of alteration is divided into several levels to obtain the degree of alteration parameters;

[0043] 140. Establish a quantitative relationship between alteration degree and thermophysical parameters, and obtain the thermal conductivity variation curves of rocks with different alterations through experiments.

[0044] 150. A heat conduction model is constructed based on the Fourier heat conduction equation, and the heterogeneity and alteration degree parameters are introduced into the heat conduction model to dynamically adjust the thermal conductivity of each alteration region. The established quantitative relationship between alteration degree and thermophysical parameters, as well as the thermal conductivity variation curves of different altered rocks, are used as the main control parameters and applied to the Fourier heat conduction equation. The Fourier heat conduction equation is discretized to obtain an improved heat conduction model, so as to realize the quantification of the relationship between the heterogeneity of altered crust thickness and thermal anomalies.

[0045] Therefore, this invention significantly improves the accuracy of calculating the relationship between crustal thickness heterogeneity and surface thermal anomalies by introducing a heterogeneous crustal model and alteration degree parameters, addressing the errors generated by traditional homogeneous silica-alumina crustal models in analyzing alteration processes. By revealing the relationship between crystalline crustal thickness heterogeneity and thermal anomalies, it deepens the understanding of crustal dynamics, especially the evolution and thermodynamic behavior of the crust in an overextended state. It can accurately quantify the relationship between crustal thickness and thermal anomalies, improving the accuracy of earthquake prediction and oil and gas resource distribution models, and providing more precise scientific basis for risk assessment and resource development in related fields.

[0046] In a preferred embodiment, such as Figure 2 As shown, the method for quantifying the relationship between the heterogeneity of altered and crystalline crust and thermal anomaly values ​​further includes the following steps:

[0047] 160. Using the improved heat conduction model, the heat flux density at the surface and at various depths was calculated. By comparing the measured surface thermal anomaly data, the thermal anomaly values ​​at the surface and at various depths were obtained.

[0048] 170. Analyze the thermal anomaly data of the alteration area, adjust the contribution of the alteration degree parameter to the thermal anomaly, and use this to correct the obtained thermal anomaly values ​​of the surface and each depth layer, and obtain the thermal anomaly value correction calculation results.

[0049] 180. The improved heat conduction model and the calculation results of the corrected thermal anomaly values ​​are compared with the measured surface thermal anomalies and crustal thickness heterogeneity to verify accuracy. By adjusting parameters such as alteration degree and thermal conductivity, the results are made closer to the measured data, and a quantitative relationship between the heterogeneity of altered and crystalline crust and thermal anomaly values ​​is established to determine the value of the relationship parameter λ.

[0050] In one specific embodiment, such as Figure 3 As shown, a geological model of a heterogeneous crystalline crust is constructed in the following manner:

[0051] 310. Obtain and analyze geophysical exploration data from continental margin regions to determine the physical changes and alteration degree of the lithosphere in the ultra-extensional region.

[0052] In practice, geophysical exploration data, including drilling and seismic profile data, is acquired from the continental margin region. Seismic and lithofacies identification and statistical analysis are conducted on crustal thickness, crustal deformation characteristics, and the distribution of serpentinized mantle emplacements, with the aim of obtaining the physical changes and alteration degree of the lithosphere in the ultra-extensional region.

[0053] 320. Based on refraction seismic data, crustal heterogeneity is divided into multiple layers or units, resulting in super-extensional units.

[0054] 330. Different alteration degree markers are added to the super-extensional unit, and corresponding lithological changes are marked to complete the geological model construction of the heterogeneous crystalline crust.

[0055] In one specific embodiment, the Fourier heat conduction equation is: Where q represents heat flux, k represents thermal conductivity, and T represents temperature gradient. The Fourier heat conduction equation is discretized using the finite element method or finite difference method, and the variation of crustal heat flux with depth and time is calculated layer by layer. Heterogeneous parameters include changes in thermophysical properties caused by vertical anisotropy in lithology and mineral facies.

[0056] In one specific embodiment, experimental and statistical methods are used to establish a quantitative relationship between alteration degree and thermophysical parameters. The thermal conductivity variation curves of different altered rocks are obtained through high-temperature experiments and applied to the heat conduction model.

[0057] The following application scenario example further illustrates this method:

[0058] Since the Late Mesozoic, the Jiangkou Basin and a certain sea basin in the northern part of a certain sea area have been influenced by the subduction of the ancient Pacific Ocean, resulting in the development of a hot Andean island arc. During the Cenozoic, they were further dragged by the subduction of the ancient sea area, developing an extensional thinning lithosphere structure, or even an over-extensional state, which caused the upwelling of the hot mantle. In the late Cenozoic, especially in the later stages of expansion, they were further influenced by magmatic intrusion. Throughout history, the Jiangkou Basin has been in a state of alternating different alterations, thus developing a heterogeneous crustal structure. The specific implementation process of the method of this invention will be explained here using the Jiangkou Basin as an example:

[0059] ① This study integrates existing OBS refraction seismic data, gravity inversion data (such as the Parker-Oldenburg method), borehole data, and regionally covered 2D and 3D multichannel reflection seismic data from a certain estuary basin and a certain sea basin to delineate and constrain the anomalous thickness of the crystalline crust, crustal deformation characteristics, and the distribution of serpentinized mantle emplacements. In particular, it focuses on the physical changes of the lithosphere in the ultra-extensional region of the estuary basin, including crustal heterogeneity classification based on data, dividing the crust of the estuary basin into multiple layers or units, such as... Figure 4 As shown, this calculation uses a crustal thickness of 20 km as the boundary for ultrathinning. Units with different degrees of alteration are added to the ultra-extension region, and the corresponding lithological changes are marked.

[0060] ②Based on the thermal conductivity and other parameters of typical rocks in a certain estuary basin and a certain sea basin, the thermal properties of different alteration layers in the basin are defined and set, including thermal conductivity and specific heat capacity.

[0061] ③ Based on the geological characteristics of crustal alteration in a certain river estuary basin and a certain sea basin, the degree of alteration is divided into several levels, such as... Figure 5As shown, the alteration zones include the unaltered near-end crust, the slightly altered necking zone with underplating, the moderately altered near-end zone with magmatic intrusion and significant thinning, and the heavily altered COT zone with serpentinization. Each alteration level corresponds to different thermophysical parameters.

[0062] ④ A quantitative relationship between alteration degree and thermophysical parameters such as thermal conductivity and specific heat capacity was established using experimental petrological statistical methods. Different alteration degrees were obtained through high-temperature experiments.

[0063] ⑤ A heat conduction model was constructed using the Fourier heat conduction equation, with input parameters including heat flux, thermal conductivity, and temperature gradient. For a model of a river mouth basin in the northern continental margin, heterogeneity and alteration degree parameters were introduced to dynamically adjust the thermal conductivity of different alteration zones within the basin. The heat conduction equation was discretized using the finite difference method, and the variation of crustal heat flux with H and T at different alterations within the river mouth basin was calculated layer by layer.

[0064] ⑥ For example Figure 6 As shown, the heat flux density at the Earth's surface and at various depths is calculated using a model. By comparing the measured surface thermal anomaly data, the influence of uneven crustal thickness on heat flux is analyzed, and the differences in surface temperature gradient and heat flux distribution caused by thickness variations are quantified.

[0065] ⑦ Analyze thermal anomaly data from an altered area in a river estuary basin and a sea basin, comparing the model calculation results with measured surface thermal anomalies and crustal thickness heterogeneity to verify the model's accuracy. By adjusting parameters such as alteration degree and thermal conductivity, the model results are made closer to the measured data. Figure 7 As shown, a quantitative relationship between the heterogeneity of altered and crystalline crust and thermal anomaly values ​​is established, the relationship parameter λ is determined, and the model is optimized and adjusted.

[0066] The above embodiments are merely illustrative of the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made based on the essence of the content of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for quantifying the relationship between the heterogeneity of altered and crystalline crust and thermal anomaly values, characterized in that, include: A geological model of a heterogeneous crystalline crust is constructed, wherein different alteration layers are marked in the geological model of the heterogeneous crystalline crust; The thermal properties of the different alteration layers are defined and set to obtain the heterogeneous parameters; Based on the geological characteristics of the altered layer, the degree of alteration is divided into several levels, and the degree of alteration parameters are obtained. A quantitative relationship between alteration degree and thermophysical parameters was established, and the thermal conductivity variation curves of different altered rocks were obtained through experiments. A heat conduction model is constructed based on the Fourier heat conduction equation. The heterogeneity and alteration degree parameters are introduced into the heat conduction model to dynamically adjust the thermal conductivity of each altered region. The established quantitative relationship between alteration degree and thermophysical parameters, as well as the thermal conductivity variation curves of different altered rocks, are used as the main control parameters and applied to the Fourier heat conduction equation. The Fourier heat conduction equation is then discretized to obtain an improved heat conduction model, thereby quantifying the relationship between the heterogeneity of altered crust thickness and thermal anomalies.

2. The method for quantifying the relationship between altered and crystalline crustal heterogeneity and thermal anomaly values ​​as described in claim 1, characterized in that, Also includes: Using the improved heat conduction model, the heat flux density at the surface and at various depths was calculated. By comparing the measured surface thermal anomaly data, the thermal anomaly values ​​at the surface and at various depths were obtained. Analyze the thermal anomaly data of the altered area, adjust the contribution of the alteration degree parameter to the thermal anomaly, and use this to correct the obtained thermal anomaly values ​​of the surface and each depth layer, and obtain the thermal anomaly value correction calculation results. The accuracy of the improved heat conduction model and the calculation results of the corrected thermal anomaly values ​​were verified by comparing them with the measured surface thermal anomalies and crustal thickness heterogeneity.

3. The method for quantifying the relationship between altered and crystalline crustal heterogeneity and thermal anomaly values ​​as described in claim 1 or 2, characterized in that, A geological model of a heterogeneous crystalline crust is constructed using the following method: To acquire and analyze geophysical exploration data from continental margin regions in order to obtain the physical changes and alteration degree of the lithosphere in the ultra-extensional region; Based on refraction seismic data, crustal heterogeneity is divided into multiple layers or units, resulting in super-extensional units. Different alteration levels were added to the super-extensional units, and corresponding lithological changes were marked to complete the geological model construction of the heterogeneous crystalline crust.

4. The method for quantifying the relationship between altered and crystalline crustal heterogeneity and thermal anomaly values ​​as described in claim 3, characterized in that, The analysis includes analysis of crustal thickness, crustal deformation characteristics, distribution of serpentinized mantle emplacement, seismic facies, lithofacies identification, and statistical analysis.

5. The method for quantifying the relationship between altered and crystalline crustal heterogeneity and thermal anomaly values ​​as described in claim 3, characterized in that, The geophysical exploration data includes drilling and seismic profile data.

6. The method for quantifying the relationship between altered and crystalline crustal heterogeneity and thermal anomaly values ​​as described in claim 1, characterized in that, The Fourier equation for heat conduction is: Where q is heat flux, k is thermal conductivity, and T is temperature gradient.

7. The method for quantifying the relationship between altered and crystalline crustal heterogeneity and thermal anomaly values ​​as described in claim 1 or 6, characterized in that, The heat conduction equation is discretized using the finite element method or finite difference method, and the changes in crustal heat flow with depth and time are calculated layer by layer.

8. The method for quantifying the relationship between altered and crystalline crustal heterogeneity and thermal anomaly values ​​as described in claim 1, characterized in that, The thermal properties of different alteration layers are defined and set based on thermal conductivity, density, and specific heat capacity.

9. The method for quantifying the relationship between altered and crystalline crustal heterogeneity and thermal anomaly values ​​as described in claim 1 or 8, characterized in that, The heterogeneity parameters include changes in thermophysical properties resulting from vertical heterogeneous lithology and mineral phase variations.

10. The method for quantifying the relationship between altered and crystalline crustal heterogeneity and thermal anomaly values ​​as described in claim 1, characterized in that, Experimental and statistical methods were used to establish a quantitative relationship between alteration degree and thermophysical parameters.

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