Coastal effect correction method, system, equipment and medium based on linear iteration

Abstract

The present application discloses a coastal effect correction method, system, equipment and medium based on linear iteration, and relates to the technical field of coastal effect correction. The method comprises a linear relationship between a magnetotelluric impedance tensor, a background impedance tensor of a real underground structure and an impedance tensor of a coastal effect, and the impedance tensor of the coastal effect is calculated according to total electromagnetic parameters and parameters excluding coastal effect, and a corrected impedance tensor excluding coastal effect is calculated according to the observed total magnetotelluric impedance tensor, and an intermediate inversion model is obtained according to a geoelectric model excluding the ocean and the corrected impedance tensor excluding coastal effect, and a magnetotelluric three-dimensional forward simulation is performed based on the intermediate inversion model and the ocean model, and the total magnetotelluric impedance tensor including the ocean effect is calculated, and a final inversion model that can more realistically reflect the underground structure of the region is determined according to the total magnetotelluric impedance tensor including the ocean effect and the observed total magnetotelluric impedance tensor.

Description

Technical Field

[0001] The present application relates to the technical field of coastal effect correction, and in particular to a coastal effect correction method, system, device and medium based on linear iteration. Background Art

[0002] In offshore areas, the presence of surrounding seas seriously affects the observed magnetotelluric response, which is caused by the strong electrical difference between the ocean and the land. The skin depth of magnetotelluric sounding can reach hundreds of kilometers. When the distance between the sounding point and the coast is less than the skin depth of the target frequency, the ocean will affect the electromagnetic field near the coast, causing the observed magnetotelluric data to be distorted. This is commonly known as the "coastal effect", which seriously affects the credibility of the deep electrical structure.

[0003] Magnetotelluric in offshore areas is affected by the coastal effect, and the measured apparent resistivity and phase data will be distorted. In the past, the TM / TE mode with less influence was usually selected or the higher frequency was intercepted for magnetotelluric inversion, resulting in the loss of model information or the inversion model with large errors, which could not truly reflect the underground structure. Therefore, when conducting magnetotelluric work in offshore areas, the coastal effect cannot be ignored and must be corrected during data processing. Summary of the invention

[0004] The purpose of this application is to provide a coastal effect correction method, system, device and medium based on linear iteration, which can obtain a final inversion model that can more realistically reflect the underground structure of the target offshore area.

[0005] To achieve the above objectives, this application provides the following solutions:

[0006] In a first aspect, the present application provides a coastal effect correction method based on linear iteration, comprising:

[0007] Establish an ocean model based on the sea area information of the target offshore area;

[0008] Establishing a geoelectric model of the target offshore area excluding the ocean, performing three-dimensional magnetotelluric forward simulation based on the geoelectric model excluding the ocean, and calculating parameters excluding coastal effects; the parameters excluding coastal effects include background electric field intensity, background magnetic field intensity, and background impedance tensor;

[0009] Based on the geoelectric model excluding the ocean and the ocean model, a three-dimensional magnetotelluric forward simulation is performed to calculate total electromagnetic parameters; the total electromagnetic parameters include the total electric field intensity including the coastal effect, the total magnetic field intensity including the coastal effect, and the total impedance tensor including the coastal effect;

[0010] Based on the linear relationship between the magnetotelluric impedance tensor, the background impedance tensor of the real underground structure and the impedance tensor of the coastal effect, the impedance tensor of the coastal effect is calculated according to the total electromagnetic parameters and the parameters excluding the coastal effect;

[0011] Calculate a corrected impedance tensor excluding the coastal effect according to the impedance tensor of the coastal effect and the observed total magnetotelluric impedance tensor;

[0012] Taking the geoelectric model excluding the ocean as the initial inversion model, performing a three-dimensional magnetotelluric inversion simulation according to the corrected impedance tensor excluding the coastal effect, and obtaining an intermediate inversion model;

[0013] Performing a three-dimensional magnetotelluric forward simulation based on the intermediate inversion model and the ocean model to calculate a total magnetotelluric impedance tensor including ocean effects;

[0014] A final inversion model is determined according to the total magnetotelluric impedance tensor including the ocean effect and the observed total magnetotelluric impedance tensor.

[0015] In a second aspect, the present application provides a coastal effect correction system based on linear iteration, comprising:

[0016] The ocean model building module is used to: build an ocean model based on the sea area information of the target offshore area;

[0017] The module for calculating the parameters excluding the coastal effect is used to establish a geoelectric model excluding the ocean in the target offshore area, perform a three-dimensional magnetotelluric forward simulation based on the geoelectric model excluding the ocean, and calculate the parameters excluding the coastal effect; the parameters excluding the coastal effect include background electric field intensity, background magnetic field intensity and background impedance tensor;

[0018] A total electromagnetic parameter calculation module is used to: perform a three-dimensional magnetotelluric forward simulation based on the geoelectric model without the ocean and the ocean model to calculate the total electromagnetic parameters; the total electromagnetic parameters include the total electric field intensity including the coastal effect, the total magnetic field intensity including the coastal effect, and the total impedance tensor including the coastal effect;

[0019] The module for calculating the impedance tensor of the coastal effect is used to calculate the impedance tensor of the coastal effect according to the total electromagnetic parameters and the parameters excluding the coastal effect based on the linear relationship between the magnetotelluric impedance tensor, the background impedance tensor of the real underground structure and the impedance tensor of the coastal effect;

[0020] A correction module, used for: calculating a corrected impedance tensor excluding the coastal effect according to the impedance tensor of the coastal effect and the observed total magnetotelluric impedance tensor;

[0021] An intermediate inversion model determination module is used to: use the geoelectric model without the ocean as the initial inversion model, perform a three-dimensional magnetotelluric inversion simulation according to the corrected impedance tensor without the coastal effect, and obtain an intermediate inversion model;

[0022] A total magnetotelluric impedance tensor calculation module including ocean effects is used to: perform magnetotelluric three-dimensional forward simulation based on the intermediate inversion model and the ocean model to calculate the total magnetotelluric impedance tensor including ocean effects;

[0023] The final inversion model determination module is used to determine the final inversion model according to the total magnetotelluric impedance tensor including the ocean effect and the observed total magnetotelluric impedance tensor.

[0024] In a third aspect, the present application provides a computer device, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the above-mentioned coastal effect correction method based on linear iteration.

[0025] In a fourth aspect, the present application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the above-mentioned coastal effect correction method based on linear iteration.

[0026] According to the specific embodiments provided in this application, this application discloses the following technical effects:

[0027] The present application provides a coastal effect correction method, system, device and medium based on linear iteration, establishes a geoelectric model excluding the ocean in the target offshore area, performs three-dimensional magnetotelluric forward simulation based on the geoelectric model excluding the ocean, calculates parameters excluding coastal effects, and the parameters excluding coastal effects include background electric field intensity, background magnetic field intensity and background impedance tensor, performs three-dimensional magnetotelluric forward simulation based on the geoelectric model excluding the ocean and the ocean model, and calculates total electromagnetic parameters; the total electromagnetic parameters include the total electric field intensity including coastal effects, the total magnetic field intensity including coastal effects and the total impedance tensor including coastal effects, and calculates the coastal effect based on the linear relationship between the magnetotelluric impedance tensor, the background impedance tensor of the real underground structure and the impedance tensor of the coastal effect according to the total electromagnetic parameters and the parameters excluding coastal effects. The impedance tensor of the coastal effect is obtained by calculating the corrected impedance tensor excluding the coastal effect according to the impedance tensor of the coastal effect and the observed total magnetotelluric impedance tensor. The geoelectric model without the ocean is used as the initial inversion model. The magnetotelluric three-dimensional inversion simulation is performed according to the corrected impedance tensor excluding the coastal effect to obtain an intermediate inversion model. The magnetotelluric three-dimensional forward simulation is performed based on the intermediate inversion model and the ocean model to calculate the total magnetotelluric impedance tensor including the ocean effect. The final inversion model is determined according to the total magnetotelluric impedance tensor including the ocean effect and the observed total magnetotelluric impedance tensor. The distortion caused by the coastal effect in the magnetotelluric response can be removed to obtain a model close to the real underground structure. There is no need to select the TM / TE mode or intercept a higher frequency for magnetotelluric inversion, and the inversion result is more reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 This is an application environment diagram of a coastal effect correction method based on linear iteration in an embodiment of the present application;

[0030] Figure 2 A schematic flow chart of a coastal effect correction method based on linear iteration provided in one embodiment of the present application;

[0031] Figure 3 A schematic diagram of a specific process of a coastal effect correction method based on linear iteration provided in one embodiment of the present application;

[0032] Figure 4 A schematic diagram of a magnetotelluric and geoelectric model containing an ocean provided in an embodiment of the present application; wherein: Figure 4(a) is a top view of the magnetotelluric geoelectric model including the ocean; Figure 4 (b) is a cross-section diagram of the magnetotelluric and geoelectric model including the ocean;

[0033] Figure 5 A schematic diagram of functional modules of a coastal effect correction system based on linear iteration provided in one embodiment of the present application;

[0034] Figure 6 A schematic diagram of the structure of a computer device provided in one embodiment of the present application. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0036] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0037] The coastal effect correction method based on linear iteration provided in the embodiment of the present application can be applied to Figure 1In the application environment shown, the terminal 102 communicates with the server 104 through a network. The data storage system can store data that the server 104 needs to process. The data storage system can be set up separately, integrated on the server 104, or placed on the cloud or other servers. The terminal 102 may send the sea area information of the target offshore area to the server 104. After the server 104 receives the sea area information of the target offshore area, for the sea area information of the target offshore area, the server 104 calculates the impedance tensor of the coastal effect according to the total electromagnetic parameters and the parameters excluding the coastal effect based on the linear relationship between the magnetotelluric impedance tensor, the background impedance tensor of the real underground structure and the impedance tensor of the coastal effect, and calculates the corrected impedance tensor excluding the coastal effect according to the observed total magnetotelluric impedance tensor, obtains the intermediate inversion model according to the geoelectric model excluding the ocean and the corrected impedance tensor excluding the coastal effect, performs magnetotelluric three-dimensional forward simulation based on the intermediate inversion model and the ocean model, calculates the total magnetotelluric impedance tensor including the ocean effect, and determines the final inversion model that can truly reflect the underground structure of the target offshore area according to the total magnetotelluric impedance tensor including the ocean effect and the observed total magnetotelluric impedance tensor. The server 104 can feed back the obtained final inversion model for the target offshore area to the terminal 102. In addition, in some embodiments, the coastal effect correction method based on linear iteration can also be implemented independently by the server 104 or the terminal 102. For example, the terminal 102 can directly perform coastal effect correction on the sea area information of the target offshore area, or the server 104 can obtain the sea area information of the target offshore area from the data storage system and perform coastal effect correction on the sea area information of the target offshore area.

[0038] The terminal 102 may be, but is not limited to, various desktop computers, laptop computers, smart phones, tablet computers, IoT devices, and portable wearable devices. The IoT devices may be smart speakers, smart TVs, smart air conditioners, smart vehicle-mounted devices, etc. The portable wearable devices may be smart watches, smart bracelets, head-mounted devices, etc. The server 104 may be implemented as an independent server or a server cluster consisting of multiple servers, or may be a cloud server.

[0039] In an exemplary embodiment, Figure 2 and Figure 3 As shown, a coastal effect correction method based on linear iteration is provided. The method is executed by a computer device, and can be executed by a computer device such as a terminal or a server alone, or by a terminal and a server together. In the embodiment of the present application, the method is applied to Figure 1 The server 104 in the example is used as an example to illustrate the method, which includes the following steps 201 to 208. Among them:

[0040] Step 201: Establish an ocean model based on the sea area information of the target offshore area.

[0041] Step 202: Establish a geoelectric model of the target offshore area excluding the ocean, perform three-dimensional magnetotelluric forward simulation based on the geoelectric model excluding the ocean, and calculate parameters excluding coastal effects; the parameters excluding coastal effects include background electric field intensity, background magnetic field intensity and background impedance tensor.

[0042] Step 203: Perform three-dimensional magnetotelluric forward simulation based on the geoelectric model excluding the ocean and the ocean model to calculate total electromagnetic parameters; the total electromagnetic parameters include the total electric field intensity including the coastal effect, the total magnetic field intensity including the coastal effect, and the total impedance tensor including the coastal effect.

[0043] Step 204: Based on the linear relationship between the magnetotelluric impedance tensor, the background impedance tensor of the real underground structure and the impedance tensor of the coastal effect, the impedance tensor of the coastal effect is calculated according to the total electromagnetic parameters and the parameters excluding the coastal effect.

[0044] Step 205: Calculate a corrected impedance tensor excluding coastal effect based on the impedance tensor of the coastal effect and the observed total magnetotelluric impedance tensor.

[0045] Step 206: Using the geoelectric model excluding the ocean as the initial inversion model, performing a three-dimensional magnetotelluric inversion simulation based on the corrected impedance tensor excluding the coastal effect, to obtain an intermediate inversion model.

[0046] Step 207: Perform three-dimensional magnetotelluric forward simulation based on the intermediate inversion model and the ocean model to calculate the total magnetotelluric impedance tensor including the ocean effect.

[0047] Step 208: Determine a final inversion model according to the total magnetotelluric impedance tensor including the ocean effect and the observed total magnetotelluric impedance tensor.

[0048] By implementing the above steps 201 to 208, the magnetotelluric impedance tensor is derived. , the background impedance tensor of the real underground structure , the impedance tensor of the coastal effect The linear relationship satisfied by the three can remove the distortion caused by the coastal effect in the magnetotelluric response, and obtain a model close to the real underground structure. There is no need to select the TM / TE mode or intercept a higher frequency for magnetotelluric inversion, and the inversion result is more reliable. In addition, the present application can also correct the coastal effect by repeatedly calculating the impedance tensor of the coastal effect and the iterative method of inversion. The calculation process of the present application only needs to include the sea area around the survey area into the forward simulation, and does not need to be included in the inversion process, which greatly reduces the amount of calculation. The final inversion model obtained in step 208 is a model that can more realistically reflect the underground structure, which can be interpreted in combination with the geological data and drilling data of the target offshore area.

[0049] Collect sea area information around the magnetotelluric survey area in the target offshore area and build an ocean model. The sea area information includes sea depth and sea resistivity.

[0050] In another exemplary embodiment of the present application, in step 203, a three-dimensional forward modeling of magnetotelluric is performed based on the geoelectric model excluding the ocean and the ocean model to calculate the total electromagnetic parameters, which specifically includes the following steps 301 to 302.

[0051] Step 301: Determine a magnetotelluric and geoelectrical model containing the ocean based on the geoelectrical model excluding the ocean and the ocean model; the magnetotelluric and geoelectrical model containing the ocean is as follows: Figure 4 As shown, Figure 4 In the figure, the vertical line area represents the ocean, the blank area represents the land, X is the direction of the coastline, Y is the direction perpendicular to the coastline, and Z is the altitude.

[0052] Step 302: Perform three-dimensional magnetotelluric forward simulation based on the ocean-containing magnetotelluric geoelectric model to calculate total electromagnetic parameters.

[0053] The magnetotelluric intensity of the crustal electrical structure can be decomposed into two parts: the background electromagnetic field and the electromagnetic field reflecting the anomaly. Therefore, the total magnetotelluric electric field intensity in the offshore area is and the total magnetic field strength It can be expressed as:

[0054] (1);

[0055] in, and The total electric field strength including the coastal effect and the total magnetic field strength including the coastal effect constitute the total electromagnetic field. and They are the background electric field intensity without coastal effect and the background magnetic field intensity without coastal effect. The background electric field intensity and the background magnetic field intensity constitute the background electromagnetic field without coastal effect. and They are the abnormal electric field intensity and the abnormal magnetic field intensity respectively, which constitute the electromagnetic field including the coastal effect.

[0056] According to the definition of magnetotelluric impedance tensor:

[0057] (2);

[0058] in, is the total magnetotelluric impedance tensor, is the background impedance tensor of the real underground structure, is the impedance tensor of the coastal effect.

[0059] Comparing the left and right sides of the upper equation in equation (1) with the lower equation, we can get:

[0060] (3);

[0061] Substituting formula (2) into formula (3) and further deducing, we can finally get:

[0062] (4);

[0063] in, Represents a unit tensor. When the geoelectric model is fixed, the ratio of the magnetic field strength of the actual underground structure to the total magnetic field strength Fixed, so it can be , then equation (4) can be simplified to equation (5), and the linear relationship between the magnetotelluric impedance tensor, the background impedance tensor of the real underground structure and the impedance tensor of the coastal effect is as follows:

[0064] (5);

[0065] in, is a constant tensor, . It can be seen that and , There is a linear relationship between the three.

[0066] Step 204 specifically includes: substituting the total electromagnetic parameters and the parameters excluding coastal effects into a linear relationship based on the magnetotelluric impedance tensor, the background impedance tensor of the real underground structure and the impedance tensor of the coastal effect, and calculating the impedance tensor of the coastal effect.

[0067] Establish a geoelectric model of the target offshore area without the ocean as the initial inversion model, and use magnetotelluric three-dimensional forward simulation to calculate the background electric field intensity without the coastal effect. , background magnetic field strength and the background impedance tensor Then, the ocean model is added to the initial inversion model, and the total electric field strength including the coastal effect is calculated using magnetotelluric three-dimensional forward simulation. , total magnetic field strength including coastal effect and the total impedance tensor including coastal effects ; The impedance tensor of the coastal effect is calculated by formula (6): , and the observed total magnetotelluric impedance tensor Substituting them into equation (7), we can calculate the corrected impedance tensor excluding the coastal effect: .

[0068] That is, by establishing a geoelectric model for offshore areas, forward calculation can be used to obtain the background electric field strength without the coastal effect. , background magnetic field strength and the background impedance tensor and the total electric field strength including the coastal effect , total magnetic field strength including coastal effect and the total impedance tensor including coastal effects , and substituting it into equation (5), we can get the impedance tensor of the coastal effect :

[0069] (6);

[0070] The impedance tensor of the coastal effect obtained by formula (6) is The total magnetotelluric impedance tensor obtained from magnetotelluric observations Substituting them into equation (5), we can obtain the corrected impedance tensor excluding the coastal effect: The calculation formula of the corrected impedance tensor excluding coastal effects is as follows:

[0071] (7);

[0072] The geoelectric model without ocean established in step 202 is used as the initial inversion model, and the corrected impedance tensor without coastal effect obtained in step 205 is used. Perform 3D magnetotelluric inversion to obtain an inversion model that reflects the underground structure, namely the intermediate inversion model. Then, add the ocean model to the intermediate inversion model and use 3D magnetotelluric forward simulation to calculate the total magnetotelluric impedance tensor including the ocean effect. .

[0073] In another exemplary embodiment of the present application, step 208 specifically includes the following steps 401 to 402:

[0074] Step 401: Calculating a coastal effect correction error according to the total magnetotelluric impedance tensor including the ocean effect and the observed total magnetotelluric impedance tensor;

[0075] Step 402: Determine whether the coastal effect correction error is greater than a set error threshold. If so, replace the geoelectric model excluding the ocean with the intermediate inversion model, and return to the step of "performing three-dimensional magnetotelluric forward simulation based on the geoelectric model excluding the ocean" until the coastal effect correction error is no greater than the set error threshold, and obtain the final inversion model; if not, determine the intermediate inversion model as the final inversion model.

[0076] Calculate the total magnetotelluric impedance tensor obtained above including the ocean effect Total magnetotelluric impedance tensor The coastal effect correction error RMS between is calculated as follows:

[0077] (8);

[0078] Where N is the frequency number, and Respectively represent the calculated i The apparent resistivity logarithm and apparent phase at each frequency point, and Respectively represent the observed i The apparent resistivity logarithm and apparent phase at each frequency point, and They represent the observation errors of the apparent resistivity logarithm and apparent phase, respectively. RMS is the coastal effect correction error, which reflects the iteration error rather than the inversion error and can be set to 5%.

[0079] If the RMS does not reach the set error threshold, the initial inversion model without the ocean established in step 202 is replaced by the intermediate inversion model, and the process returns to step 202 until the RMS reaches the set error threshold, thereby obtaining a final inversion model close to the actual underground structure.

[0080] The present application also provides an application scenario, which applies the above-mentioned coastal effect correction method based on linear iteration. Specifically: the coastal effect correction method based on linear iteration provided in this embodiment can be applied in the coastal effect correction scenario. The coastal effect correction scenario includes an information acquisition link and a coastal effect correction link; the sea area information of the target offshore area enters the coastal effect correction link from the information acquisition link to obtain the final inversion model. The coastal effect correction method based on linear iteration provided in this embodiment belongs to the machine marking link in the coastal effect correction link. Specifically, in the process of correcting the coastal effect link for the target offshore area, the impedance tensor of the coastal effect can be calculated according to the total electromagnetic parameters and the parameters excluding the coastal effect based on the linear relationship between the magnetotelluric impedance tensor, the background impedance tensor of the real underground structure and the impedance tensor of the coastal effect, and the corrected impedance tensor excluding the coastal effect is calculated according to the observed total magnetotelluric impedance tensor. The intermediate inversion model is obtained according to the geoelectric model excluding the ocean and the corrected impedance tensor excluding the coastal effect. The magnetotelluric three-dimensional forward simulation is performed based on the intermediate inversion model and the ocean model to calculate the total magnetotelluric impedance tensor including the ocean effect. The final inversion model that can more realistically reflect the underground structure of the target offshore area is determined according to the total magnetotelluric impedance tensor including the ocean effect and the observed total magnetotelluric impedance tensor.

[0081] Based on the same inventive concept, the embodiment of the present application also provides a coastal effect correction system based on linear iteration for implementing the coastal effect correction method based on linear iteration involved above. The implementation scheme for solving the problem provided by the system is similar to the implementation scheme recorded in the above method, so the specific limitations in one or more embodiments of the coastal effect correction system based on linear iteration provided below can refer to the limitations of the coastal effect correction method based on linear iteration above, and will not be repeated here.

[0082] In an exemplary embodiment, Figure 5 As shown, a coastal effect correction system based on linear iteration is provided, comprising:

[0083] The ocean model building module T1 is used to: build an ocean model based on the sea area information of the target offshore area;

[0084] The module T2 for calculating the parameters excluding the coastal effect is used to establish a geoelectric model excluding the ocean in the target offshore area, perform a three-dimensional magnetotelluric forward simulation based on the geoelectric model excluding the ocean, and calculate the parameters excluding the coastal effect; the parameters excluding the coastal effect include the background electric field intensity, the background magnetic field intensity and the background impedance tensor;

[0085] The total electromagnetic parameter calculation module T3 is used to: perform a three-dimensional forward modeling of magnetotelluric based on the geoelectric model without the ocean and the ocean model to calculate the total electromagnetic parameters; the total electromagnetic parameters include the total electric field intensity including the coastal effect, the total magnetic field intensity including the coastal effect and the total impedance tensor including the coastal effect;

[0086] The impedance tensor calculation module T4 of the coastal effect is used to calculate the impedance tensor of the coastal effect according to the total electromagnetic parameters and the parameters excluding the coastal effect based on the linear relationship between the magnetotelluric impedance tensor, the background impedance tensor of the real underground structure and the impedance tensor of the coastal effect;

[0087] The correction module T5 is used to calculate the corrected impedance tensor excluding the coastal effect according to the impedance tensor of the coastal effect and the observed total magnetotelluric impedance tensor;

[0088] The intermediate inversion model determination module T6 is used to: use the geoelectric model without the ocean as the initial inversion model, perform a three-dimensional magnetotelluric inversion simulation according to the corrected impedance tensor without the coastal effect, and obtain an intermediate inversion model;

[0089] A total magnetotelluric impedance tensor calculation module T7 including ocean effect is used to: perform magnetotelluric three-dimensional forward simulation based on the intermediate inversion model and the ocean model to calculate the total magnetotelluric impedance tensor including ocean effect;

[0090] The final inversion model determination module T8 is used to determine the final inversion model according to the total magnetotelluric impedance tensor including the ocean effect and the observed total magnetotelluric impedance tensor.

[0091] In an exemplary embodiment, a computer device is provided. The computer device may be a server or a terminal. The internal structure diagram thereof may be as follows: Figure 6As shown. The computer device includes a processor, a memory, an input / output interface (Input / Output, referred to as I / O) and a communication interface. The processor, the memory and the input / output interface are connected through a system bus, and the communication interface is connected to the system bus through the input / output interface. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store coastal effect correction data. The input / output interface of the computer device is used to exchange information between the processor and an external device. The communication interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, a coastal effect correction method based on linear iteration is implemented.

[0092] Those skilled in the art will understand that Figure 6 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0093] In an exemplary embodiment, a computer device is further provided, including a memory and a processor, wherein a computer program is stored in the memory, and the processor implements the steps in the above-mentioned method embodiments when executing the computer program.

[0094] In an exemplary embodiment, a computer-readable storage medium is provided, storing a computer program, and when the computer program is executed by a processor, the steps in the above method embodiments are implemented.

[0095] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of relevant data must comply with relevant regulations.

[0096] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to the memory, database or other medium used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetoresistive random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM may be in various forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM).

[0097] The database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database. The non-relational database may include a distributed database based on blockchain, etc., but is not limited thereto. The processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, etc., but is not limited thereto.

[0098] The technical features of the above embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0099] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A coastal effect correction method based on linear iteration, characterized in that: The coastal effect correction method based on linear iteration includes: Establish an ocean model based on the sea area information of the target offshore area; Establishing a geoelectric model of the target offshore area excluding the ocean, performing three-dimensional magnetotelluric forward simulation based on the geoelectric model excluding the ocean, and calculating parameters excluding coastal effects; the parameters excluding coastal effects include background electric field intensity, background magnetic field intensity, and background impedance tensor; Based on the geoelectric model excluding the ocean and the ocean model, a three-dimensional magnetotelluric forward simulation is performed to calculate total electromagnetic parameters; the total electromagnetic parameters include the total electric field intensity including the coastal effect, the total magnetic field intensity including the coastal effect, and the total impedance tensor including the coastal effect; Based on the linear relationship between the magnetotelluric impedance tensor, the background impedance tensor of the real underground structure and the impedance tensor of the coastal effect, the impedance tensor of the coastal effect is calculated according to the total electromagnetic parameters and the parameters excluding the coastal effect; the linear relationship between the magnetotelluric impedance tensor, the background impedance tensor of the real underground structure and the impedance tensor of the coastal effect is determined as follows: The magnetotelluric intensity of the crustal electrical structure is decomposed into two parts: the background electromagnetic field and the electromagnetic field reflecting the anomaly. The total electric field intensity of the magnetotelluric in the offshore area and the total magnetic field strength It is expressed as: （1）； in, and The total electric field strength including the coastal effect and the total magnetic field strength including the coastal effect constitute the total electromagnetic field. and They are the background electric field intensity without coastal effect and the background magnetic field intensity without coastal effect. The background electric field intensity and the background magnetic field intensity constitute the background electromagnetic field without coastal effect. and They are abnormal electric field intensity and abnormal magnetic field intensity, which constitute the electromagnetic field including the coastal effect; According to the definition of magnetotelluric impedance tensor: （2）； in, is the total magnetotelluric impedance tensor, is the background impedance tensor of the real underground structure, is the impedance tensor of the coastal effect; Comparing the left and right sides of the upper equation in equation (1) with the lower equation, we can get: （3）； Substituting formula (2) into formula (3) and further deducing, we can finally get: （4）； in, Represents a unit tensor; when the geoelectric model is fixed, the ratio of the magnetic field intensity of the actual underground structure to the total magnetic field intensity Fixed, order , then equation (4) is simplified to equation (5), and the linear relationship between the magnetotelluric impedance tensor, the background impedance tensor of the real underground structure and the impedance tensor of the coastal effect is as follows: （5）； in, is the magnetotelluric impedance tensor; and , There is a linear relationship between the three; Calculate a corrected impedance tensor excluding the coastal effect according to the impedance tensor of the coastal effect and the observed total magnetotelluric impedance tensor; Taking the geoelectric model excluding the ocean as the initial inversion model, performing a three-dimensional magnetotelluric inversion simulation according to the corrected impedance tensor excluding the coastal effect, and obtaining an intermediate inversion model; Performing a three-dimensional magnetotelluric forward simulation based on the intermediate inversion model and the ocean model to calculate a total magnetotelluric impedance tensor including ocean effects; A final inversion model is determined according to the total magnetotelluric impedance tensor including the ocean effect and the observed total magnetotelluric impedance tensor.

2. The coastal effect correction method based on linear iteration according to claim 1, characterized in that: The final inversion model is determined according to the total magnetotelluric impedance tensor including the ocean effect and the observed total magnetotelluric impedance tensor, specifically comprising: Calculating a coastal effect correction error based on the total magnetotelluric impedance tensor including ocean effect and the observed total magnetotelluric impedance tensor; Determine whether the coastal effect correction error is greater than a set error threshold. If so, replace the geoelectric model excluding the ocean with the intermediate inversion model, and return to the step of "performing three-dimensional magnetotelluric forward simulation based on the geoelectric model excluding the ocean" until the coastal effect correction error is no greater than the set error threshold, and obtain the final inversion model; if not, determine the intermediate inversion model as the final inversion model.

3. The coastal effect correction method based on linear iteration according to claim 1, characterized in that: Based on the geoelectric model excluding the ocean and the ocean model, a three-dimensional magnetotelluric forward simulation is performed to calculate total electromagnetic parameters, specifically including: Determining a magnetotelluric and geoelectrical model containing an ocean based on the geoelectrical model excluding the ocean and the ocean model; Based on the ocean-containing magnetotelluric geoelectric model, a three-dimensional magnetotelluric forward simulation is performed to calculate the total electromagnetic parameters.

4. The coastal effect correction method based on linear iteration according to claim 1, characterized in that: Based on the linear relationship between the magnetotelluric impedance tensor, the background impedance tensor of the real underground structure and the impedance tensor of the coastal effect, the impedance tensor of the coastal effect is calculated according to the total electromagnetic parameters and the parameters excluding the coastal effect, specifically including: The total electromagnetic parameters and the parameters excluding coastal effect are substituted into a linear relationship based on the magnetotelluric impedance tensor, the background impedance tensor of the real underground structure and the impedance tensor of the coastal effect to calculate the impedance tensor of the coastal effect.

5. The coastal effect correction method based on linear iteration according to claim 1, characterized in that: The calculation formula of the corrected impedance tensor excluding coastal effects is as follows: ； in, is the corrected impedance tensor excluding coastal effects, To observe the total magnetotelluric impedance tensor, is the impedance tensor of the coastal effect, , is the background magnetic field strength without coastal effects, is the total magnetic field strength including coastal effects.

6. The coastal effect correction method based on linear iteration according to claim 1, characterized in that: The sea area information includes sea water depth and sea water resistivity.

7. A coastal effect correction system based on linear iteration, characterized in that: The coastal effect correction system based on linear iteration includes: The ocean model building module is used to: build an ocean model based on the sea area information of the target offshore area; The module for calculating the parameters excluding the coastal effect is used to establish a geoelectric model excluding the ocean in the target offshore area, perform a three-dimensional magnetotelluric forward simulation based on the geoelectric model excluding the ocean, and calculate the parameters excluding the coastal effect; the parameters excluding the coastal effect include background electric field intensity, background magnetic field intensity and background impedance tensor; A total electromagnetic parameter calculation module is used to: perform a three-dimensional magnetotelluric forward simulation based on the geoelectric model without the ocean and the ocean model to calculate the total electromagnetic parameters; the total electromagnetic parameters include the total electric field intensity including the coastal effect, the total magnetic field intensity including the coastal effect, and the total impedance tensor including the coastal effect; The module for calculating the impedance tensor of the coastal effect is used to calculate the impedance tensor of the coastal effect according to the total electromagnetic parameters and the parameters excluding the coastal effect based on the linear relationship between the magnetotelluric impedance tensor, the background impedance tensor of the real underground structure and the impedance tensor of the coastal effect; A correction module, used for: calculating a corrected impedance tensor excluding the coastal effect according to the impedance tensor of the coastal effect and the observed total magnetotelluric impedance tensor; An intermediate inversion model determination module is used to: use the geoelectric model without the ocean as the initial inversion model, perform a three-dimensional magnetotelluric inversion simulation according to the corrected impedance tensor without the coastal effect, and obtain an intermediate inversion model; A total magnetotelluric impedance tensor calculation module including ocean effects is used to: perform magnetotelluric three-dimensional forward simulation based on the intermediate inversion model and the ocean model to calculate the total magnetotelluric impedance tensor including ocean effects; The final inversion model determination module is used to determine the final inversion model according to the total magnetotelluric impedance tensor including the ocean effect and the observed total magnetotelluric impedance tensor.

8. A computer device comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the coastal effect correction method based on linear iteration described in any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the coastal effect correction method based on linear iteration described in any one of claims 1 to 6 is implemented.

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