CN117969609A - Seawater resistivity detection method based on electromagnetic field, storage medium and electronic equipment - Google Patents
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Abstract
The application provides a seawater resistivity detection method based on an electromagnetic field, a storage medium and electronic equipment, wherein the method comprises the following steps: acquiring an electric field and a magnetic field formed by a natural source or an artificial field source at a remote area observation point; based on the electric field and the magnetic field, determining apparent resistivity of the observation point; fitting a visual resistivity curve based on the visual resistivity of the observation point; and acquiring the sea water depth of the observation point, and determining the sea water longitudinal resistivity from the observation point to the sea floor based on the sea water depth and the apparent resistivity curve. Therefore, the detection efficiency of the sea water resistivity can be effectively improved, and the method can be used as an effective complementary method and means of the existing mainstream detection method, and can provide more suitable detection means under various different conditions in an actual detection scene.
Description
Technical Field
The application relates to the technical field of sea water detection, in particular to a sea water resistivity detection method based on an electromagnetic field, a storage medium and electronic equipment.
Background
The ocean covers 71% of the earth's surface and is the second space for human survival. The vertical distance from the sea surface to the sea bottom is the sea water depth, and the topography of the sea bottom is intuitively reflected. Seawater resistivity is an important parameter that visually reflects the marine environment. Seawater resistivity (seawater conductivity can be further determined) and seawater depth are both the basis for performing ocean exploration, ocean military operations, and other related problems.
Marine electromagnetic field refers to electromagnetic fields that exist in a marine environment due to a man-made or natural field source, including electric and magnetic fields, collectively referred to as marine electromagnetic fields. In the ocean development activities, a kind of radio waves have the characteristics of weakening, strong penetrating power and the like, have been widely focused in recent years, and are rapidly developed, so that the method can be widely applied to the fields of navigation, mineral exploration, underwater military target detection and the like.
Currently, the seawater resistivity detection means is mainly determined by scattered sampling, and the problems of difficult deep sampling, difficult comprehensive sampling and the like exist, so that the overall seawater resistivity in the whole sea depth cannot be comprehensively reflected.
Disclosure of Invention
The embodiment of the application aims to provide a seawater resistivity detection method, a storage medium and electronic equipment based on an electromagnetic field, which are used for constructing a seawater resistivity detection scheme based on the electromagnetic field by fully excavating hidden information in the ocean electromagnetic field, and rapidly calculating to obtain the seawater resistivity as an effective complementary method and means of the existing mainstream detection method.
In order to achieve the above object, an embodiment of the present application is achieved by:
in a first aspect, an embodiment of the present application provides a method for detecting resistivity of seawater based on an electromagnetic field, which is characterized by comprising:
Acquiring an electric field and a magnetic field formed by a natural source or an artificial field source at a remote area observation point;
Based on the electric field and the magnetic field, determining apparent resistivity of the observation point;
Fitting a visual resistivity curve based on the visual resistivity of the observation point;
And acquiring the sea water depth of the observation point, and determining the sea water longitudinal resistivity from the observation point to the sea floor based on the sea water depth and the apparent resistivity curve.
With reference to the first aspect, in a first possible implementation manner of the first aspect, determining a apparent resistivity of the observation point based on the electric field and the magnetic field includes:
the incident electric field and magnetic field formed by the natural source or artificial field source in the far zone are similar to plane wave vertical incidence, and the wave impedance is as follows:
Wherein E x is the electric field horizontal component in the x direction; e y is the electric field horizontal component in the y direction; h x is the magnetic field horizontal component in the x direction; h y is the magnetic field horizontal component in the y-direction;
The apparent resistivity at the observation point is:
Where ρ s is apparent resistivity, ω is angular frequency, μ is permeability, and Z obs is wave impedance at the observation point.
With reference to the first aspect, in a second possible implementation manner of the first aspect, fitting a apparent resistivity curve based on the apparent resistivity of the observation point based on the electric field and the magnetic field includes: and (5) performing primary data processing on the apparent resistivity, and fitting by adopting a cubic curve.
With reference to the second possible implementation manner of the first aspect, in a third possible implementation manner of the first aspect, determining a sea water longitudinal resistivity from the observation point to the sea floor based on the sea water depth and the apparent resistivity curve based on the electric field and the magnetic field includes:
determining the value range of the sea water resistivity;
taking Deltaρ as a value interval from one end of the value range to the other end, and recording the seawater resistivity of the nth value as
Seawater resistivity for nth valueThe sea water resistivity/>, was calculated using the following formulaCorresponding first three frequencies/>
Wherein,Is sea water resistivity/>A frequency corresponding to the ith intersection of the apparent resistivity curves,Alpha i is the attenuation coefficient corresponding to the ith intersection point,/>H w is the sea water depth, μ 0 is the vacuum permeability;
Based on frequency Determining corresponding apparent resistivity value/>, from the apparent resistivity curve
If the seawater resistivity is the nth valueAnd the corresponding apparent resistivity value/>Meeting the contract conditions, determining/>Is the longitudinal resistivity rho w of the sea water; if the seawater resistivity is the nth value/>And the corresponding apparent resistivity valueThe sea water resistivity of the (n+1) th time value is not satisfied with the appointed conditionAnd judging the convention condition until the seawater longitudinal resistivity rho w meeting the convention condition is found.
With reference to the third possible implementation manner of the first aspect, in a fourth possible implementation manner of the first aspect, the agreed condition is that the sea water resistivitySimultaneously satisfying the following two inequalities:
Wherein, Respectively represents the sea water resistivity/>At frequency/>Corresponding apparent resistivity value in the apparent resistivity curve,/>Respectively represents the sea water resistivity/>At the frequency ofCorresponding apparent resistivity value in the apparent resistivity curve,/> Respectively represents the sea water resistivity/>At frequency/>The corresponding apparent resistivity values in the apparent resistivity curves.
With reference to the third possible implementation manner of the first aspect, in a fifth possible implementation manner of the first aspect, the seawater resistivity ranges from [0.198,1.02] to a value interval Δρ=0.01.
With reference to the third possible implementation manner of the first aspect, in a sixth possible implementation manner of the first aspect, after determining the longitudinal resistivity ρ w of the seawater, the method further includes:
Based on the seawater longitudinal resistivity ρ w, the seawater longitudinal conductivity σ w is calculated using the following formula:
wherein sigma w is the sea water longitudinal conductivity.
With reference to the first aspect, in a seventh possible implementation manner of the first aspect, there is a sea water-seabed medium at the observation point, and the seabed medium is one or more layers.
In a second aspect, an embodiment of the present application provides a storage medium, where the storage medium is installed in a device, and includes a stored program, where the program, when executed, controls the device in which the storage medium is located to execute the electromagnetic field based sea water resistivity detection method according to any one of the first aspect or the possible implementation manners of the first aspect.
In a third aspect, an embodiment of the present application provides an electronic device, including a memory for storing information including program instructions, and a processor for controlling execution of the program instructions, which when loaded and executed by the processor, implement the steps of the electromagnetic field based sea water resistivity detection method according to the first aspect or any one of the possible implementations of the first aspect.
The beneficial effects are that:
1. Firstly, converting an electromagnetic field signal series through electric field and magnetic field signals formed at an observation point of a remote area by a natural source or an artificial field source acquired in the air or sea water to obtain a apparent resistivity curve of the observation point. And then carrying out theoretical deduction, and establishing a theoretical calculation formula for excavating the sea water depth and sea water resistivity information according to the apparent resistivity curve, so that after the sea water depth of the observation point is obtained, the sea water longitudinal resistivity from the observation point to the sea bottom can be determined based on the sea water depth and the apparent resistivity curve (combined with the theoretical calculation formula). Therefore, the detection efficiency of the sea water resistivity can be effectively improved, and the method can be used as an effective complementary method and means of the existing mainstream detection method, and can provide more suitable detection means under various different conditions in an actual detection scene.
2. When the theoretical calculation formula constructed by deduction is utilized to reversely calculate the sea water resistivity, three intersection points (the relation when the apparent resistivity is equal to the sea water resistivity, the attenuation coefficient value and the like are discussed in detail in the theoretical deduction process) generated between the apparent resistivity curve fitted by adopting a cubic curve and the sea water resistivity straight line are utilized to calculate the frequency corresponding to each intersection point by utilizing the formula, and the appointed condition is designed to judge whether the sea water resistivity value reaches the current optimal value, so that the reverse calculation of the sea water resistivity is realized. In addition, a verification scheme can be designed to judge whether the value of the seawater resistivity meets the requirement or not, and if the value of the seawater resistivity does not meet the requirement, the accuracy of interval value can be adjusted, so that the seawater resistivity which meets the condition better is determined, the seawater longitudinal resistivity is calculated, and the accuracy can be ensured and the detection accuracy is improved.
In order to make the above objects, features and advantages of the present application more comprehensible, preferred embodiments accompanied with figures are described in detail below.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments of the present application will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and should not be considered as limiting the scope, and other related drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a flowchart of a seawater resistivity detection method based on an electromagnetic field according to an embodiment of the present application.
Fig. 2 is a schematic diagram of a sea water-seabed medium.
Fig. 3 is a schematic view of the apparent resistivity curve of the observation point in example 1.
Fig. 4 is a schematic diagram of apparent resistivity values corresponding to three intersections calculated in example 1.
Fig. 5 is a schematic view of the apparent resistivity curve of the observation point in example 2.
Fig. 6 is a schematic diagram of apparent resistivity values corresponding to three intersections calculated in example 2.
Detailed Description
The technical solutions in the embodiments of the present application will be described below with reference to the accompanying drawings in the embodiments of the present application.
Referring to fig. 1, fig. 1 is a flowchart of a seawater resistivity detection method based on an electromagnetic field according to an embodiment of the present application. In this embodiment, the seawater resistivity detection method based on the electromagnetic field is applied to an electronic device (such as a server or a terminal), and the method may include step S10, step S20, step S30, and step S40.
First, the electronic device may run step S10.
Step S10: an electric field and a magnetic field formed at an observation point of a remote zone by a natural source or an artificial field source are obtained.
In the present embodiment, the electronic apparatus can acquire an electric field and a magnetic field (electric field signal and magnetic field signal) formed by a natural source or an artificial field source at the observation point of the far zone. Natural sources: under the action of thunder and lightning phenomenon and solar wind, a global natural alternating electromagnetic field is distributed in the earth, the frequency range is wide, and plane waves can be regarded as incidence when the electromagnetic field reaches the earth. The artificial field source remote region can be defined by referring to a controllable source audio magnetotelluric sounding method: vertical area: the equatorial region of the power supply dipole, r >4 delta, is the far region; coaxial region: the axial region of the feed dipole, r >5 delta, is the far region. Where r is the distance from the observation point to the power supply dipole, delta is the skin depth,Ρ is the resistivity and f is the frequency.
After the electric field and the magnetic field are obtained, the electronic device may run step S20.
Step S20: based on the electric field and the magnetic field, the apparent resistivity of the observation point is determined.
In this embodiment, the electronic device may convert the electric field and the magnetic field (electric field signal and magnetic field signal) at the observation point into the corresponding apparent resistivity.
Since all macroscopic electromagnetic phenomena satisfy the Maxwell's equation set, consisting of faraday's law, ampere's law, coulomb's law and magnetic flux continuity principle, the differential form is:
Wherein, Is Hamiltonian, is/>, in rectangular coordinate systemE is the electric field strength, B is the magnetic induction strength, D is the electric displacement, H is the magnetic field strength, and ρ is the free charge density.
The three constitutive relations are:
D＝εE， (5)
B＝μH， (6)
J＝σE， (7)
Where ε is the dielectric constant, μ is the magnetic permeability, and σ is the electrical conductivity.
The electromagnetic field can be converted into a combination of a series of harmonic fields in a time domain through Fourier transformation, and the time harmonic factor is e -iωt (or e iωt), so that the electric field strength and the magnetic field strength can be respectively expressed as:
E＝E0e-iωt， (8)
H＝H0e-iωt， (9)
The Maxwell equation set for the harmonic field is then:
The incident electromagnetic field formed by the remote area of the natural source or the artificial field source can be approximately plane wave vertical incidence, and then the wave impedance of the electromagnetic field at the observation point is as follows:
Wherein E x is the electric field horizontal component in the x direction; e y is the electric field horizontal component in the y direction; h x is the magnetic field horizontal component in the x direction; h y is the magnetic field horizontal component in the y-direction.
The apparent resistivity at the observation point is:
Where ρ s is the apparent resistivity, ω is the angular frequency, ω=2pi f, f is the frequency, μ is the permeability, and Z obs is the wave impedance at the observation point, i.e., Z in the foregoing equation (14).
For a seawater-subsea two-layer medium (as shown in fig. 2), the impedance value at the surface of the second layer seawater medium is therefore:
Wherein Z 2 (0) is the ground wave impedance, H 1 is the attenuation factor, ω is the angular frequency, ε 1 is the dielectric constant of the first layer medium (i.e. sea water), ε 2 is the dielectric constant of the second layer medium (i.e. sea floor), μ is the magnetic permeability of the medium, μ in k 1 is the magnetic permeability of the first layer medium, μ in k 2 is the magnetic permeability of the second layer medium, μ is not distinguished here because μ is very small (the influence on the calculation result is very small), μ is used uniformly, μ defaults to vacuum magnetic permeability μ 0,σ1 is the first layer medium conductivity, h 1 is the thickness of the first layer medium, σ 2 is the second layer medium conductivity, and i is the imaginary unit.
Order the
Analytical formulae show that when cos2α=0, i.e.When the method is used, the following steps are included:
A1＝-B2， (22)
A2＝-B1， (23)
Then there are:
I.e. the modes of the two complex numbers are equal: |a|= |b|.
At this time, the apparent resistivity of the observation point is equal to the resistivity of seawater, namely:
ρs＝|Z2(0)|2/(ωμ)＝ρw， (25)
wherein ρ w is the sea water resistivity at the observation point.
The incident electromagnetic field formed by the natural source or artificial field source far zone can be approximately plane wave vertical incidence, in the marine electromagnetic environment, the sea water is a medium conductor, the conductivity distribution is generally between 1 and 5S/m, the permeability is generally considered as the permeability mu 0 in vacuum, the relative dielectric constant is about 80, at the moment, omega epsilon < <1, the displacement current can be ignored, namely, the iomega epsilon in each formula can be ignored. Then, when the sea water depth is known, the sea water resistivity is reversely calculated according to the apparent resistivity curve and the sea water depth to obtain the sea water longitudinal resistivity, and the sea water longitudinal conductivity from the observation point to the sea bottom can be further calculated by utilizing the sea water longitudinal resistivity (the reciprocal relation with the sea water conductivity).
From the theory above, it is known that when apparent resistivity is equal to sea water resistivity, there are Taking the first 3 equivalent points from low frequency to high frequency,/> The method comprises the following steps:
in order to realize the detection of the sea water resistivity, the converted apparent resistivity needs to be fitted to obtain an apparent resistivity curve. Accordingly, the electronic device may run step S30.
Step S30: and fitting a visual resistivity curve based on the visual resistivity of the observation point.
In this embodiment, the electronic device may perform preliminary data processing on the apparent resistivity, and fit the apparent resistivity with a cubic curve to obtain a curve ρ s of the apparent resistivity. The apparent resistivity obtained at the observation point is the apparent resistivity of many frequencies containing the sea water and the submarine medium information, so as to be used for fitting the apparent resistivity curve.
After obtaining the apparent resistivity curve, the electronic device may run step S40.
Step S40: and acquiring the sea water depth of the observation point, and determining the sea water longitudinal resistivity from the observation point to the sea floor based on the sea water depth and the apparent resistivity curve.
For example, the electronic device may determine the sea water longitudinal resistivity from the observation point to the sea floor based on the sea water depth and apparent resistivity curves.
Firstly, the value range of the seawater resistivity can be determined, and the seawater conductivity distribution is generally between 1 and 5S/m, and the seawater resistivity is the inverse of the seawater conductivity, so the value range of the seawater resistivity is exemplified by [0.198,1.02] Ω & m, and the range is based on the extension of 0.2 to 1.0, and the seawater resistivity can be ensured to be within the value range.
After determining the seawater resistivity range, the electronic device may take Δρ (for example, the value interval Δρ=0.01, or Δρ=0.001, for example, Δρ=0.01 but not limited thereto) from one end (for example, 0.198) of the seawater resistivity range as the value interval to the other end (for example, to the 1.02 end), and the seawater resistivity of the nth value is recorded as
Then, the seawater resistivity for the nth valueThe electronic device can calculate the sea water resistivity/>, using the following formulaCorresponding first three frequencies/>
Wherein,Is sea water resistivity/>A frequency corresponding to the ith intersection of the apparent resistivity curves,Alpha i is the attenuation coefficient corresponding to the ith intersection point,/>H w is the sea water depth and μ 0 is the vacuum permeability. The formula (27) is obtained by deforming the formula (26), and the specific character is changed by the sea water resistivity/>, which corresponds to the nth valueAnd the deformation is made.
Thereafter, the electronic device may be frequency-basedDetermining corresponding apparent resistivity value/>, from the apparent resistivity curveThen, judging constraint conditions, wherein the constraint conditions are designed as follows:
sea water resistivity Whether the following inequality is satisfied at the same time:
Wherein, Respectively represents the sea water resistivity/>At frequency/>Corresponding apparent resistivity value in the apparent resistivity curve,/>Respectively represents the sea water resistivity/>At the frequency ofCorresponding apparent resistivity value in the apparent resistivity curve,/> Respectively represents the sea water resistivity/>At frequency/>The corresponding apparent resistivity values in the apparent resistivity curves.
If the seawater resistivity is the nth valueAnd the corresponding apparent resistivity value/>Meeting the contract conditions, the electronic device can determine/>Is the sea water longitudinal resistivity ρ w.
If the seawater resistivity is the nth valueAnd the corresponding apparent resistivity value/>The electronic device can take the value of the sea water resistivity/>, which is n+1st time, without meeting the agreed conditionAnd judging the convention condition until the seawater longitudinal resistivity rho w meeting the convention condition is found.
After determining the seawater longitudinal resistivity ρ w, the electronic device can further determine the seawater longitudinal conductivity from the observation point to the sea floor based on the seawater longitudinal resistivity ρ w.
For example, the electronics can calculate the seawater longitudinal conductivity σ w based on the seawater longitudinal resistivity ρ w using the following formula:
wherein sigma w is the sea water longitudinal conductivity.
Therefore, the longitudinal resistivity of the seawater from the observation point to the seabed can be detected based on the apparent resistivity curve and the seawater depth, and the longitudinal conductivity of the seawater from the observation point to the seabed can be further detected.
The present solution is illustrated below by way of two examples:
Example 1: a sea-water-seabed medium model (the seabed medium is a layer, i.e. only comprises one layer), the sea resistivity is 1 Ω·m, the depth is 100m, the seabed medium resistivity is 10 Ω·m, the sea observation point apparent resistivity curve (obtained by fitting the actual observation apparent resistivity curve in actual application, the apparent resistivity data used as an example is directly obtained by calculation from the model constructed by way of example and cannot be regarded as limiting the application) is shown in fig. 3.
The seawater resistivity is taken as [0.198,1.02] in the range of the interval Δρ=0.01, and the electronic device can take the value from 0.198, take one value every time the interval Δρ is taken, and gradually take 1.02 (if the last value is insufficient for the interval Δρ, i.e. after the interval Δρ, the value exceeds 1.02, the last endpoint value is taken directly, i.e. 1.02).
By the calculation procedure given above, i.e. by calculating the sea water resistivity using equation (27)Corresponding first three frequencies/>Based on frequency/>Determining corresponding apparent resistivity value from the apparent resistivity curveAs shown in fig. 4, the constraint condition is determined by using inequalities (28) and (29), and after the seawater longitudinal resistivity satisfying the constraint condition is finally determined, the seawater longitudinal conductivity is further calculated by using a formula (30), so that the seawater resistivity ρ w =0.998Ω·m (the difference from the set value 1 Ω·m is 0.2%), and correspondingly, the seawater longitudinal conductivity σ w =1.002 (the difference from the set value 1S/m is 0.2%).
Example 2: establishing a sea water-seabed medium model (the seabed medium is three layers, namely the seabed medium comprises three layers), wherein the sea water resistivity is 1 omega-m, the depth is 100m, the seabed first layer medium resistivity is 10 omega-m, the depth is 1000m, the seabed second layer medium resistivity is 30 omega-m, the depth is 500m, and the seabed third layer medium resistivity is 50 omega-m. The apparent resistivity curve of the sea surface observation point (obtained by fitting the actual observed apparent resistivity curve in actual application, the apparent resistivity data used as an example here is directly obtained by calculation from a model constructed by way of example, and cannot be regarded as limiting the present application) is shown in fig. 5.
The seawater resistivity is taken as [0.198,1.02] in the range of the interval Δρ=0.01, and the electronic device can take the value from 0.198, take one value every time the interval Δρ is taken, and gradually take 1.02 (if the last value is insufficient for the interval Δρ, i.e. after the interval Δρ, the value exceeds 1.02, the last endpoint value is taken directly, i.e. 1.02).
By the calculation procedure given above, i.e. by calculating the sea water resistivity using equation (27)Corresponding first three frequencies/>Based on frequency/>Determining corresponding apparent resistivity value from the apparent resistivity curveAs shown in fig. 6, constraint conditions are determined by using inequalities (28) and (29), after the seawater longitudinal resistivity satisfying the constraint conditions is finally determined, the seawater longitudinal conductivity is further calculated by using a formula (30), and finally the seawater resistivity ρ w =0.998Ω·m (the difference from the set value 1 Ω·m is 0.2%) is obtained, and correspondingly, the seawater longitudinal conductivity σ w =1.002 (the difference from the set value 1S/m is 0.2%).
The embodiment provides a storage medium, which is installed in a device and comprises a stored program, wherein the device where the storage medium is controlled to execute the seawater resistivity detection method based on the electromagnetic field of the embodiment when the program runs.
And the embodiment also provides an electronic device, which comprises a memory and a processor, wherein the memory is used for storing information comprising program instructions, and the processor is used for controlling execution of the program instructions, and the program instructions realize the steps of the electromagnetic field-based seawater resistivity detection method when being loaded and executed by the processor.
In summary, the embodiment of the application provides a seawater resistivity detection method, a storage medium and an electronic device based on an electromagnetic field, which convert electromagnetic field signal series to obtain a apparent resistivity curve of an observation point through electric field and magnetic field signals formed at the observation point of a remote zone by a natural source or an artificial field source collected in air or seawater. And then carrying out theoretical deduction, and establishing a theoretical calculation formula for excavating the sea water depth and sea water resistivity information according to the apparent resistivity curve, so that after the sea water depth of the observation point is obtained, the sea water longitudinal resistivity from the observation point to the sea bottom can be determined based on the sea water depth and the apparent resistivity curve (combined with the theoretical calculation formula). Therefore, the detection efficiency of the sea water resistivity can be greatly improved, and the method can be used as an effective complementary method and means of the existing mainstream detection method, and can provide more suitable detection means under various different conditions in an actual detection scene.
When the theoretical calculation formula constructed by deduction is utilized to reversely calculate the sea water resistivity, three intersection points (the relation when the apparent resistivity is equal to the sea water resistivity, the attenuation coefficient value and the like are discussed in detail in the theoretical deduction process) generated between the apparent resistivity curve fitted by adopting a cubic curve and the sea water resistivity straight line are utilized to calculate the frequency corresponding to each intersection point by utilizing the formula, and the appointed condition is designed to judge whether the sea water resistivity value reaches the current optimal value, so that the reverse calculation of the sea water resistivity is realized. In addition, a verification scheme can be designed to judge whether the value of the seawater resistivity meets the requirement or not, and if the value of the seawater resistivity does not meet the requirement, the accuracy of interval value can be adjusted, so that the seawater resistivity which meets the condition better is determined, the seawater longitudinal resistivity is calculated, and the accuracy can be ensured and the detection accuracy is improved.
In this document, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions.
The above description is only an example of the present application and is not intended to limit the scope of the present application, and various modifications and variations will be apparent to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.
Claims (10)
1. A seawater resistivity detection method based on an electromagnetic field, comprising:
Acquiring an electric field and a magnetic field formed by a natural source or an artificial field source at a remote area observation point;
Based on the electric field and the magnetic field, determining apparent resistivity of the observation point;
Fitting a visual resistivity curve based on the visual resistivity of the observation point;
And acquiring the sea water depth of the observation point, and determining the sea water longitudinal resistivity from the observation point to the sea floor based on the sea water depth and the apparent resistivity curve.
2. The electromagnetic field based seawater resistivity detection method of claim 1, wherein determining apparent resistivity of the observation point based on the electric field and the magnetic field comprises:
the incident electric field and magnetic field formed by the natural source or artificial field source in the far zone are similar to plane wave vertical incidence, and the wave impedance is as follows:
Wherein E x is the electric field horizontal component in the x direction; e y is the electric field horizontal component in the y direction; h x is the magnetic field horizontal component in the x direction; h y is the magnetic field horizontal component in the y-direction;
The apparent resistivity at the observation point is:
Where ρ s is apparent resistivity, ω is angular frequency, μ is permeability, and Z obs is wave impedance at the observation point.
3. The electromagnetic field based seawater resistivity detection method of claim 1, wherein fitting a apparent resistivity curve based on apparent resistivity of the observation point includes:
and (5) performing primary data processing on the apparent resistivity, and fitting by adopting a cubic curve.
4. A seawater resistivity detection method based on an electromagnetic field as claimed in claim 3, wherein determining the seawater longitudinal resistivity from the observation point to the sea floor based on the seawater depth and apparent resistivity curves comprises:
determining the value range of the sea water resistivity;
taking Deltaρ as a value interval from one end of the value range to the other end, and recording the seawater resistivity of the nth value as
Seawater resistivity for nth valueThe sea water resistivity/>, was calculated using the following formulaCorresponding first three frequencies/>
Wherein,Is sea water resistivity/>A frequency corresponding to the ith intersection of the apparent resistivity curves,Alpha i is the attenuation coefficient corresponding to the ith intersection point,/>H w is the sea water depth, μ 0 is the vacuum permeability;
Based on frequency Determining corresponding apparent resistivity value/>, from the apparent resistivity curve
If the seawater resistivity is the nth valueAnd the corresponding apparent resistivity value/>Meeting the contract conditions, determining/>Is the longitudinal resistivity rho w of the sea water; if the seawater resistivity is the nth value/>And the corresponding apparent resistivity valueThe sea water resistivity of the (n+1) th time value is not satisfied with the appointed conditionAnd judging the convention condition until the seawater longitudinal resistivity rho w meeting the convention condition is found.
5. The method for electromagnetic field based seawater resistivity detection as claimed in claim 4, wherein the contracted condition is seawater resistivitySimultaneously satisfying the following two inequalities:
Wherein, Respectively represents the sea water resistivity/>At frequency/>Corresponding apparent resistivity value in the apparent resistivity curve,/>Respectively represents the sea water resistivity/>At the frequency ofCorresponding apparent resistivity value in the apparent resistivity curve,/> Respectively represents the sea water resistivity/>At frequency/>The corresponding apparent resistivity values in the apparent resistivity curves.
6. The electromagnetic field based seawater resistivity test method of claim 4, wherein the seawater resistivity is in the range of [0.198,1.02] with a value interval Δρ=0.01.
7. The electromagnetic field based seawater resistivity detection method of claim 4, further comprising, after determining the seawater longitudinal resistivity ρ w:
Based on the seawater longitudinal resistivity ρ w, the seawater longitudinal conductivity σ w is calculated using the following formula:
wherein sigma w is the sea water longitudinal conductivity.
8. The electromagnetic field based seawater resistivity test method of claim 1, wherein there is a seawater-seafloor medium at the observation point, the seafloor medium being one or more layers.
9. A storage medium, characterized in that the storage medium is installed in a device, comprising a stored program, wherein the program, when run, controls the device in which the storage medium is located to perform the electromagnetic field based sea water resistivity detection method according to any one of claims 1 to 8.
10. An electronic device comprising a memory for storing information including program instructions and a processor for controlling execution of the program instructions, characterized by: the program instructions, when loaded and executed by a processor, carry out the steps of the electromagnetic field based sea water resistivity detection method according to any one of claims 1 to 8.
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