CN111929737B

CN111929737B - Method and device for remotely detecting layer interface position and electromagnetic information

Info

Publication number: CN111929737B
Application number: CN202010983039.5A
Authority: CN
Inventors: 唐章宏; 许月晨; 王芬
Original assignee: Beijing Weizhi Jiachen Technology Development Co ltd
Current assignee: Beijing Weizhi Jiachen Technology Development Co ltd
Priority date: 2020-09-17
Filing date: 2020-09-17
Publication date: 2021-01-15
Anticipated expiration: 2040-09-17
Also published as: CN111929737A

Abstract

The embodiment of the application discloses a method and a device for remotely detecting the interface position and electromagnetic information of a layer, wherein the method comprises the steps of establishing a model of a transmitting coil wound by a vertical shaft in a symmetrical mode and a remote detection fractional turn receiving coil wound by a non-axial symmetry mode and coaxial and parallel to the transmitting coil, and eliminating direct coupling electromotive force generated by the transmitting coil on the receiving coil according to the model; calculating a reflection field of the transmitting coil at the receiving coil by adopting a mirror image method according to the receiving coil model and the transmitting coil model; calculating the total electric field generated by the transmitting coil at the receiving coil by adopting a field superposition principle; calculating the induced electromotive force of the receiving coil by adopting Gaussian integral according to the total electric field; based on the method, the amplitude and the phase angle of the induced electromotive force of the receiving coil under each working frequency are solved by emitting electromagnetic waves with different working frequencies, and then the position and the electromagnetic information of the interface of the dielectric layer are solved. The method and the device can quickly calculate the position and the electromagnetic information of the medium layer interface, and are favorable for remote and efficient detection.

Description

Method and device for remotely detecting layer interface position and electromagnetic information

Technical Field

The invention relates to the technical field of layer interface detection, in particular to a method and a device for remotely detecting layer interface position and electromagnetic information.

Background

With the rapid development of detection technology, remote edge detection and imaging systems have become hot issues, and especially for the fields of airplanes, radars, underwater submarines, well logging and the like, the development of imaging and remote detection of three-dimensional vector fields becomes very important research content. In the geological exploration process, when the long-distance detection logging can measure the tectonic geologic body in a well, the measuring range of the conventional logging technology is improved to dozens of meters from about one meter around the well.

However, in the process of implementing the present invention, the inventor finds that, in the existing remote detection technology, when detecting the interface position of the dielectric layer and the electromagnetic information, due to the existence of more than one medium, the calculated medium model is no longer an axisymmetric model, the calculation difficulty is high, a three-dimensional numerical solution mode must be adopted to solve the field domain during the simulation calculation, and particularly, for the large electric size and the small electric size with a relatively high contrast ratio, the number of divided grid nodes is too large, which correspondingly causes an excessively large calculation amount and a low calculation speed, and thus the requirement of remote and efficient detection is difficult to meet.

Disclosure of Invention

The embodiment of the application provides a method and a device for remotely detecting the position and the electromagnetic information of a layer interface, which can quickly calculate the position and the electromagnetic information of a medium layer interface and are beneficial to remote and efficient detection.

In a first aspect, an embodiment of the present application provides a method for remotely detecting a layer interface location and electromagnetic information, where the method includes:

establishing a model of an axisymmetrically wound transmitting coil and a model of a non-axisymmetrically wound far detection fractional turn receiving coil which is coaxial and parallel to the transmitting coil, and eliminating direct coupling electromotive force generated by the transmitting coil to the receiving coil according to the receiving coil based on the models of the transmitting coil and the receiving coil;

calculating a reflection field of the transmitting coil at the receiving coil by adopting a mirror image method according to the models of the receiving coil and the transmitting coil;

calculating a total electric field generated by the transmitting coil at the receiving coil according to the calculated reflection field by adopting a field superposition principle;

calculating the induced electromotive force of the receiving coil by adopting Gaussian integral according to the total electric field at the receiving coil;

and according to the induced electromotive force, by transmitting electromagnetic waves with different working frequencies, solving the amplitude and the phase angle of the induced electromotive force of the receiving coil under each working frequency, and according to the amplitude and the phase angle of the induced electromotive force, solving the position and the electromagnetic information of the interface of the dielectric layer.

As a possible implementation, the model of the non-axisymmetrically wound far detecting fractional turn receive coil is represented as:

the discs on which the receiving coils are wound being divided intoN>An even number of sector areas passing through the center of a circle, wherein the serial numbers of the sector areas are arranged clockwise;

each turn of the receiving coil is divided intoN1 fractional sub-turn, each fractional sub-turn being wound in a sector, the fractional sub-turns of two adjacent sectors being wound in opposite directions, and the sectors being wound in opposite directionsNEmptying; each fractional sub-turn comprises a circumferential arc part and a radial straight line part, wherein the circumferential arc part is wound on the circumferential part of the sector area, and the radial straight line part is wound on the radial tangent plane part of the sector area passing through the center of a circle;

sector area 1 &N-1 fractional sub-turn ratios of the windings respectivelyn ₁～n _N-1The ratio ofn _iSatisfy the requirement of

And is

In the formulaiIs shown asiA sector-shaped area is formed by the circular arc-shaped area,n _irepresenting a sector areaiThe number of the corresponding fractional turns is,Nthe number of the sector areas.

As a possible implementation manner, the eliminating, according to the receiving coil, the direct-coupled electromotive force generated by the transmitting coil to the receiving coil based on the model of the transmitting coil and the receiving coil includes:

the electric field generated by the transmitting coil which is coaxial and parallel to the receiving coil in the uniform medium is a concentric circle on the plane where the remote detection receiving coil is located, all radial straight line parts of the receiving coil passing through the center of the concentric circle are perpendicular to the direction of the electric field, all circumferential arc parts are parallel to the direction of the electric field, according to the winding direction of the receiving coil, the integral result of the electric field along the receiving coil is 0, correspondingly, the induced electromotive force received by the receiving coil is 0, and the direct coupling electromotive force generated by the transmitting coil to the receiving coil is eliminated.

As a possible implementation, in the calculating the reflected field of the transmitting coil at the receiving coil by using the mirror image method according to the model of the receiving coil and the transmitting coil, the determining a relationship between the mirror image source of the transmitting coil and the real source includes:

in a medium model comprising at least two layers of media, introducing a virtual mirror image transmitting coil which is in mirror symmetry with a transmitting coil in a first layer of media into a second layer of media, naming a real transmitting coil as a real source, naming the mirror image transmitting coil as a mirror image source, and replacing the second layer of media with the first layer of media, wherein the medium model is an axisymmetric model, and a relational expression between the mirror image source of the transmitting coil and the real source is as follows:

，

in the formula (I), the compound is shown in the specification,I ₂is the current of the mirror image source,I ₁in order to be the current of the real source,

is the reflection coefficient of the first layer medium and the second layer medium,

is expressed as

Wherein, in the step (A),

is the wave impedance in the first layer of medium,

is the wave impedance in the second layer of medium,

，

，

and

the magnetic permeability of the first layer medium and the second layer medium respectively,

and

complex dielectric constants of the first layer medium and the second layer medium respectively, and the expression is

，

Wherein

And

the real parts of the dielectric constants, σ, of the first and second layers of medium₁And σ₂The electrical conductivity of the first layer of medium and the second layer of medium respectively,

is the angular frequency of the electromagnetic wave, j is the imaginary unit, j²=-1。

As a possible implementation manner, the solving of the amplitude and the phase angle of the induced electromotive force of the receiving coil at each operating frequency by emitting electromagnetic waves with different operating frequencies according to the induced electromotive force, and the solving of the position and the electromagnetic information of the dielectric layer interface according to the amplitude and the phase angle of the induced electromotive force includes:

setting the distance between the layer interface and the transmitting coil to d meters, wherein the electromagnetic information of the medium layer interface comprises the conductivity sigma of the first layer medium₁And the electrical conductivity σ of the second layer medium₂；

Transmitting electromagnetic waves of at least two different operating frequencies by a transmitting coil, and generating a receiving coilThe phase angle of the induced electromotive force is recorded as

And

the wavelength of the electromagnetic wave at the first operating frequency in the first layer of medium is

The electromagnetic wave at the second working frequency has a wavelength in the first layer of medium

Wherein, in the step (A),

the first operating frequency is the wavelength in vacuum,

、

the relative permeability and the relative permittivity of the first layer of medium,

a wavelength in vacuum for a second operating frequency;

the phase angle of the electromagnetic wave at the first operating frequency varying by 2 x d

And the phase angle of the electromagnetic wave at the second operating frequency is changed to

At the layer interface, the phase angle of the reflection coefficient at the first operating frequency is

The phase angle of the reflection coefficient at the second operating frequency is

The equations (1) to (3) are listed according to the variation rule of phase angle amplitude of the electromagnetic wave in the medium:

in the equation (1),

in the equation (2),

in the equation (3),

in the formula (I), the compound is shown in the specification,

presentation pair

Taking a real part of the signal,

presentation pair

Taking a real part of the signal,real(V₁) Is shown as pair V₁Taking a real part of the signal,real(V₂) Is shown as pair V₂Taking the real part, V₁Is an induced electromotive force of the receiving coil at a first operating frequency, V₂The induced electromotive force of the receiving coil at the second operating frequency,

、

respectively at a first operating frequency andthe reflection coefficient of the lower layer interface of the second working frequency to the electromagnetic wave is respectively expressed as follows:

，

wherein

，

，

，

，

Representing the complex permittivity of the first layer of dielectric at a first operating frequency,

representing the complex permittivity of the first layer of dielectric at a second operating frequency,

representing the complex permittivity of the second layer of dielectric at the first operating frequency,

representing the complex permittivity of the second layer of dielectric at the second operating frequency,

、

is as followsReal part of dielectric constant, σ, of one layer of dielectric and a second layer of dielectric₁、σ₂Is the electrical conductivity of the first layer of medium and the second layer of medium,

、

respectively the angular frequency of the first operating frequency and the angular frequency of the second operating frequency,

and

permeability, k, of the first and second layer of medium, respectively₁And k₂Propagation constants of electromagnetic waves with first working frequency and electromagnetic waves with second working frequency in the first layer medium respectively are expressed as follows:

and

j is the imaginary unit, j²=-1；

Solving equations (1) to (3) of the nonlinear equation system by an iterative method to obtain the distance d between the interface of the medium layer and the transmitting coil and the conductivity sigma of the first layer medium₁And the electrical conductivity σ of the second layer medium₂。

In a second aspect, an embodiment of the present application provides an apparatus for remotely detecting a layer interface location and electromagnetic information, the apparatus comprising:

the first processing module is used for establishing a model of an axisymmetrically wound transmitting coil and a model of a non-axisymmetrically wound far detection fractional turn receiving coil which is coaxial and parallel to the transmitting coil, and eliminating direct coupling electromotive force generated by the transmitting coil to the receiving coil according to the receiving coil based on the models of the transmitting coil and the receiving coil;

the second processing module is used for calculating the reflection field of the transmitting coil at the receiving coil by adopting a mirror image method according to the models of the receiving coil and the transmitting coil;

the third processing module is used for calculating the total electric field generated by the transmitting coil at the receiving coil according to the calculated reflection field by adopting a field superposition principle;

the fourth processing module is used for calculating the induced electromotive force of the receiving coil by adopting Gaussian integration according to the total electric field of the receiving coil;

and the fifth processing module is used for solving the amplitude and the phase angle of the induced electromotive force of the receiving coil under each working frequency by transmitting electromagnetic waves with different working frequencies according to the induced electromotive force, and solving the position and the electromagnetic information of the medium layer interface according to the amplitude and the phase angle of the induced electromotive force.

And is

As a possible implementation, the eliminating, by the first processing module, the direct-coupled electromotive force generated by the transmitting coil to the receiving coil according to the receiving coil based on the model of the transmitting coil and the receiving coil includes:

the first processing submodule is used for enabling an electric field generated by a transmitting coil coaxial and parallel to a receiving coil in a uniform medium to be concentric in the plane where the remote detection receiving coil is located, all radial straight line parts of the receiving coil passing through the center of the concentric circle are perpendicular to the direction of the electric field, all circumferential arc parts are parallel to the direction of the electric field, according to the winding direction of the receiving coil, the integral result of the electric field along the receiving coil is 0, correspondingly, the induced electromotive force received by the receiving coil is 0, and the direct-coupled electromotive force generated by the transmitting coil to the receiving coil is eliminated.

As a possible implementation manner, in the second processing module, the calculating, according to the models of the receiving coil and the transmitting coil, the reflected field of the transmitting coil at the receiving coil by using a mirroring method includes determining a relationship between a mirror source of the transmitting coil and a real source, and the determining a relationship between a mirror source of the transmitting coil and a real source includes:

the second processing submodule is used for introducing a virtual mirror image transmitting coil which is in mirror symmetry with the transmitting coil in the first layer of medium into the second layer of medium in a medium model comprising at least two layers of media, naming the real transmitting coil as a real source, naming the mirror image transmitting coil as a mirror image source, and replacing the second layer of medium with the first layer of medium, so that the medium model is an axisymmetric model, wherein the relational expression between the mirror image source of the transmitting coil and the real source is as follows:

，

is expressed as

，

Is the wave impedance in the first layer of medium,

is the wave impedance in the second layer of medium, wherein,

，

，

and

and

，

Wherein

And

As a possible implementation, the fifth processing module includes:

Electromagnetic waves with at least two different working frequencies are transmitted by the transmitting coil, and the phase angle of induced electromotive force generated by the receiving coil is recorded as

And

Wherein, in the step (A),

the first operating frequency is the wavelength in vacuum,

、

a wavelength in vacuum for a second operating frequency;

in the equation (1),

in the equation (2),

in the equation (3),

in the formula (I), the compound is shown in the specification,

presentation pair

Taking a real part of the signal,

presentation pair

、

the reflection coefficients of the lower layer interface to the electromagnetic wave at the first working frequency and the second working frequency are respectively expressed as follows:

，

wherein

，

，

，

，

、

is the real part of the dielectric constant, σ, of the first and second layers of medium₁、σ₂Is the electrical conductivity of the first layer of medium and the second layer of medium,

、

and

and

j is the imaginary unit, j²=-1；

The embodiment of the application has the following beneficial effects:

according to the embodiment of the application, a model of a transmitting coil wound by a shaft symmetry is established, a model of a remote detection receiving coil wound by a non-shaft symmetry and coaxial and parallel with the transmitting coil is established, and based on the models of the transmitting coil and the receiving coil, direct coupling electromotive force generated by the transmitting coil to the receiving coil is eliminated according to the receiving coil; calculating a reflection field of the transmitting coil at the receiving coil by adopting a mirror image method according to the models of the receiving coil and the transmitting coil; calculating a total electric field generated by the transmitting coil at the receiving coil according to the calculated reflection field by adopting a field superposition principle; calculating the induced electromotive force of the receiving coil by adopting Gaussian integral according to the total electric field at the receiving coil; according to the induced electromotive force, by emitting electromagnetic waves with different working frequencies, the amplitude and the phase angle of the induced electromotive force of the receiving coil under each working frequency are solved, and according to the amplitude and the phase angle of the induced electromotive force, the position and the electromagnetic information of the medium layer interface are solved.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

FIG. 1 is a schematic flow chart diagram illustrating an embodiment of a method for remotely detecting layer interface position and electromagnetic information provided herein;

fig. 2 is a schematic model diagram of a non-axisymmetric remote detection receiver coil with N =4 in an embodiment of a method for remotely detecting a layer interface position and electromagnetic information provided in the present application;

FIG. 3 is a schematic diagram of a concentric electric field generated by a transmitting coil at a receiving coil in a homogeneous medium according to an embodiment of the method for remotely detecting layer interface position and electromagnetic information provided by the present application;

FIG. 4 is a schematic diagram of a conventional circular coil placed in an electric field;

FIG. 5 is a schematic diagram of a receiver coil placed in an electric field in an embodiment of a method for remotely detecting layer interface location and electromagnetic information provided herein;

FIG. 6a is a schematic diagram of an electric field at a receiver coil in the presence of a layer interface in an embodiment of a method for remotely detecting a position of a layer interface and electromagnetic information provided herein;

FIG. 6b is a diagram illustrating a directly coupled electric field background signal at a receiver coil in an embodiment of a method for remotely detecting layer interface position and electromagnetic information provided herein;

FIG. 6c is a diagram illustrating background signals of a reflected field at a receiver coil in an embodiment of a method for remotely detecting layer interface position and electromagnetic information provided herein;

FIG. 7 is a schematic view of a media model in an embodiment of a method for remotely detecting layer interface position and electromagnetic information provided herein;

FIG. 8 is a schematic view of a media model without consideration of a second layer of media in an embodiment of a method for remotely sensing layer interface location and electromagnetic information provided herein;

FIG. 9 is a schematic diagram of a model after a mirror image method is adopted when a second layer medium is considered in an embodiment of a method for remotely detecting layer interface position and electromagnetic information provided by the present application;

FIG. 10 is a schematic diagram of the variation of the induced electromotive force amplitude of the receiving coil and the distance between the layer interfaces in an embodiment of a method for remotely detecting the position and electromagnetic information of the layer interfaces provided in the present application;

FIG. 11 is a schematic diagram illustrating a phase angle of an induced electromotive force of a receiving coil and a distance change of a layer interface in an embodiment of a method for remotely detecting a position of the layer interface and electromagnetic information according to the present disclosure;

fig. 12 is a schematic structural diagram of an embodiment of a method for remotely detecting a layer interface location and electromagnetic information provided in the present application.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be described in detail by embodiments with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, "first", "second", "third", "fourth", "fifth", and the like are used only for distinguishing one from another, and do not indicate the degree of importance, the order, and the like thereof.

The division of the modules herein is merely a division of logical functions, and other divisions may be possible in actual implementation, for example, a plurality of modules may be combined or integrated in another system. Modules described as separate components may or may not be physically separate. Therefore, some or all of the modules can be selected according to actual needs to implement the scheme of the embodiment.

Referring to fig. 1-11, embodiments of the present application provide a method for remotely detecting layer interface position and electromagnetic information; as shown, the method mainly comprises:

By adopting the method, the position and the electromagnetic information of the medium layer interface can be rapidly calculated, and the method is favorable for remote and efficient detection.

the discs on which the receiving coils are wound being divided intoN>An even number of sector areas passing through the center of a circle, wherein the serial numbers of the sector areas are arranged clockwise;Nis an even number;

And is

As a possible implementation manner, the eliminating, according to the receiving coil, the direct-coupled electromotive force generated by the transmitting coil to the receiving coil based on the model of the transmitting coil and the receiving coil may include:

By adopting the method, the direct coupling electromotive force generated by the transmitting coil to the receiving coil can be completely eliminated, and the interference of the direct coupling signal to the reflected signal is avoided, so that the receiving coil can not effectively measure the reflected signal, and the electromagnetic information error of the layer interface is prevented from being larger.

In an electric field generated by a uniform field or a coaxial and parallel transmitting coil in a uniform medium, magnetic fluxes passing through N fan-shaped regions are equal, the induced electromotive force received by the receiving coil is 0 according to the winding direction of the receiving coil, and the direct-coupled electromotive force generated by the transmitting coil to the receiving coil is eliminated.

The integration result of the electric field along the receiving coil is explained as 0, as follows:

the induced electromotive force generated by the receiving coil is expressed as

In the formulaEThe electric field strength at the receiver coil, as a vector,dlis the product of the receiving coilsIs divided into units of vectors whenEAnddlwhen the included angle of the directions is less than 90 degrees, the dot product result of the two is positive whenEAnddlwhen the included angle of the directions is larger than 90 degrees, the dot product result of the two is negative, and the induced electromotive force can be obtained by integrating one circle around the receiving coil.

FIG. 3 is a schematic diagram of a concentric electric field generated by a transmitting coil at a receiving coil in a homogeneous medium according to an embodiment of the method for remotely detecting layer interface position and electromagnetic information provided by the present application. Fig. 4 is a schematic view of a conventional circular coil placed in an electric field. As shown in the figure, the conventional circular receiving coil cannot eliminate the direct-coupled electromotive force because the direction of the concentric electric field is completely the same as the integral path of the circular coil, wherein the integral path is clockwise along the coil, and the electric field is positive along the coil integral result. Fig. 5 is a schematic diagram of a receiving coil placed in an electric field in an embodiment of a method for remotely detecting a layer interface position and electromagnetic information provided in the present application, where the electric field is integrated by 0 along the coil, where the linear portion of the receiving coil integrates: the electric field lines always being perpendicular to the linear part of the receiving coil, i.e.EAnddlthe included angle of the directions is 90 degrees, and the dot product integral result of the two directions is 0; integration of the arc part of the receiving coil: the coil circular arc part has clockwise and anticlockwise direction, and the electric field is positive along clockwise circular arc integral result, and is negative along anticlockwise circular arc integral result, because the number of turns when the coiling direction is for following the pointer and anticlockwise is the same, for example, 2 circles are coiled altogether clockwise to the coil, 2 circles are coiled altogether to the anticlockwise, and the integral result sum is 0.

As a possible implementation, in the calculating the reflected field of the transmitting coil at the receiving coil by using the mirror image method according to the model of the receiving coil and the transmitting coil, the determining a relationship between the mirror image source of the transmitting coil and the real source may include:

，

is expressed as

Wherein, in the step (A),

is the wave impedance in the first layer of medium,

is the wave impedance in the second layer of medium,

，

，

and

and

，

Wherein

And

By adopting the method, the influence of the second layer medium on the medium model can be eliminated, so that the calculated model can adopt the fast algorithm of the axisymmetric model to realize fast and high-precision calculation of the reflection field, and the method is favorable for remote and efficient detection.

As a possible implementation, in the calculating the reflected field of the transmitting coil at the receiving coil by using the mirror image method, the calculation model used is as follows:

the relative dielectric constants of the first layer of medium and the second layer of medium are both 5, and the relative magnetic conductivities of the first layer of medium and the second layer of medium are both 1; the conductivity of the first layer of medium is 0.01S/m, and the conductivity of the second layer of medium is 0.5S/m; the coordinates of the circle center of the transmitting coil are (0, 0, 0), the coordinates of the circle center of the receiving coil are (0, 0, 0.05), the radiuses of the transmitting coil and the receiving coil are both 0.03m, the number of turns of the transmitting coil is 100, and the number of turns of the receiving coil is 50; the distance from the second layer interface to the z axis is gradually increased from 0.05m to 30 m; the transmitting coil current is 1A sine alternating current and the frequency is 100 kHz.

As a possible implementation, the calculating the total electric field generated by the transmitting coil at the receiving coil by using the field superposition principle includes: and calculating the total electric field generated by the real source and the mirror image source at the receiving coil by adopting a mirror image method by adopting a field superposition principle.

To be provided withNCoil model of =4, arc portion 0 toπThe calculation is performed by taking/2 as an example, as follows:

calculating induced electromotive force by Gaussian integration, and receiving induced electromotive force of coilVThe concrete expression is as follows:

，

in the formula (I), the compound is shown in the specification,Eto receive the strength of the electric field at the coil,dlis an integration unit of the receiving coil,lfor the length of the receive coil, the above equation is converted to a function with respect to angle, resulting in:

，

wherein

For receiving coils at an angleθThe vector mode of the tangential component of the electric field strength,Rwhich is the radius of the coil,

by adopting the Gaussian transformation, the method has the advantages of simple operation,

，

the transformed result is:

，

representing the field strength cut as an integrandVector modulo to the component;

is an integral variable

As a function of (a) or (b),

namely the total electric field after superposition;

using gaussian integration yields:

，

wherein

Is a weight factor of the gaussian integral and,

is a Gaussian point

The vector mode of the tangential component of the electric field strength of (a), wherein the electric field at a gaussian point needs to be transformed to the electric field at the actual coordinates, i.e.

Wherein

Is a Gaussian point

Corresponding to the coordinates of the sampling point at the actual receiving coil.

In the case of a layer interface in the vicinity of the coil, the layer interface reflects the electromagnetic wave generated by the transmitting coil, which electromagnetic wave is generated by a non-uniform and non-concentric circle with respect to the receiving coil, and therefore an induced electromotive force is generated in the coil. In the absence of a layer interface, the transmitting coil in the homogeneous medium generates a concentric electric field, as shown in fig. 3; when a layer interface exists, an electric field image at the receiving coil is as shown in fig. 6a, and fig. 6a is a schematic diagram of an electric field at the receiving coil when the layer interface exists in the embodiment of the method for remotely detecting the position of the layer interface and the electromagnetic information provided by the present application, that is, a schematic diagram of an electric field at the receiving coil obtained by using a field superposition principle; fig. 6b is a schematic diagram of a directly coupled electric field background signal at a receiving coil in an embodiment of a method for remotely detecting a layer interface location and electromagnetic information provided herein, fig. 6c is a schematic diagram of a reflected electric field background signal at a receiving coil in an embodiment of a method for remotely detecting a layer interface location and electromagnetic information provided herein, as shown in fig. 6a, 6b and 6c, fig. 6a is composed of fig. 6b and 6c, fig. 6b is a schematic diagram of a directly coupled electric field background signal at a receiving coil, independent of a layer interface, fig. 6c is a schematic diagram of a reflected electric field background signal at a receiving coil, dependent on a layer interface; wherein the direct coupling electric field is much larger than the reflection field, especially at larger layer distances, the direct coupling electric field is 1E4 times or even larger than the reflection field, and the reflection field is hardly detected if the direct coupling electric field is not eliminated. In order to accurately measure the layer interface information, a direct coupling field needs to be eliminated, which cannot be achieved by a traditional circular coil, and the receiving coil disclosed by the embodiment of the application can achieve the purpose of eliminating direct coupling electromotive force.

Specifically, the calculation of the reflected field of the transmitting coil at the receiving coil by using the mirror image method is described in detail as follows:

because the reflection field at the receiving coil is difficult to calculate due to the existence of the layer interface, the medium model is not an axisymmetric model any more, a three-dimensional numerical method is needed for solving, the calculation amount is huge, the calculation speed is low, the efficiency is low, and in order to calculate quickly, the mirror image method is adopted to solve the problem.

Referring to fig. 7-9, fig. 7 is a schematic diagram of a medium model in an embodiment of a method for remotely detecting a layer interface location and electromagnetic information provided in the present application, and fig. 8 is a schematic diagram of a method for remotely detecting a layer interface location and electromagnetic information provided in the present applicationFig. 9 is a model schematic diagram obtained after a mirror image method is adopted when the second layer medium is considered in the embodiment of the method for remotely detecting the interface position of the layer and the electromagnetic information provided by the present application. The idea of the mirror image method is to introduce a mirror image source in the second layer medium, the size of the mirror image source is equal to that of the transmitting coil, the mirror image source and the transmitting coil are symmetrical about the layer interface, and the relationship between the mirror image source and the transmitting coil is

The second layer of medium can be transformed into the first layer of medium, and the medium model is changed from non-axisymmetric to axisymmetric, as shown in fig. 9. The schematic diagram of the field calculated after mirroring at the receiving coil is shown in fig. 6a, wherein the schematic diagram of the directly coupled electric field background signal of the transmitting coil at the receiving coil is shown in fig. 6b, the schematic diagram of the field background signal reflected by the mirror source at the receiving coil is shown in fig. 6c, and the schematic diagram of the resultant field is shown in fig. 6 a.

And

Wherein, in the step (A),

the first operating frequency is the wavelength in vacuum,

、

a wavelength in vacuum for a second operating frequency;

equation (1)，

In the equation (2),

in the equation (3),

in the formula (I), the compound is shown in the specification,

presentation pair

Taking a real part of the signal,

presentation pair

、

，

，

wherein

，

，

，

，

、

、

and

and

j is the imaginary unit, j²=-1；

The model used for the calculation is as follows: the relative dielectric constants of the first layer of medium and the second layer of medium are both 5, and the relative magnetic conductivities of the first layer of medium and the second layer of medium are both 1; the conductivity of the first layer of medium is 0.01S/m, and the conductivity of the second layer of medium is 0.5S/m; the coordinates of the circle center of the transmitting coil are (0, 0, 0), the coordinates of the circle center of the receiving coil are (0, 0, 0.05), the radiuses of the transmitting coil and the receiving coil are both 0.03m, the number of turns of the transmitting coil is 100, and the number of turns of the receiving coil is 50; the distance from the second layer interface to the z axis is 10 m; the transmitting coil current 1A is a sinusoidal alternating current with frequencies of 100kHz and 200 kHz. Calculating to obtain the induced electromotive force V under two working frequencies₁=0.1716E-3+0.1848E-3iV and V₂=0.3580E-3+0.1358E-3iV, the phase angle changes are

=0.7485 and

and (5) =1.2083, and substituting equations (1), (2) and (3) to obtain a result.

Due to the adoption of the non-axisymmetrical receiving coil, the direct coupling electromotive force generated by the transmitting coil in the receiving coil is zero, and signals received by the receiving coil are all from reflected waves, so that the position of a layer interface and the dielectric conductivity can be calculated through the amplitude and the phase angle of the induced electromotive force. Fig. 10 is a schematic diagram of the amplitude of the induced electromotive force of the receiving coil and the distance change of the layer interface in an embodiment of a method for remotely detecting the position and the electromagnetic information of the layer interface provided in the present application, and as shown in the figure, the diagram is an image of the amplitude change of the induced electromotive force of the receiving coil when the distance from the layer interface to the z-axis is 0 to 30 m. Fig. 11 is a schematic diagram of a phase angle of an induced electromotive force of a receiving coil and a distance change of a layer interface in an embodiment of a method for remotely detecting a position of the layer interface and electromagnetic information provided in the present application, where in fig. 11, the distance from the layer interface to a z-axis is 0 to 30 m. It can be seen from fig. 10 that the amplitude of the induced electromotive force of the receiving coil gradually decreases as the layer interface distance increases, and at 30m, the amplitude of the single-turn receiving coil is about 1 e-6V, which can effectively identify the medium layer interface information; as can be seen from fig. 11, as the layer interface distance increases, the phase angle of the electromotive force induced in the receiver coil gradually decreases and then increases in the opposite direction, within 30m, the variation range is-pi/2, the medium interface information can be effectively identified through the phase angle variation, for electromagnetic fields with higher operating frequencies and higher dielectric resistivities, electromagnetic fields traveling over distances of 30m or more, reflected to the receiver coil, the phase difference exceeds 360 degrees, firstly, the attenuation condition of the electromagnetic field is judged according to the amplitude of the induced electromotive force generated by the receiving coil, the propagation distance of the electromagnetic wave is judged, an evaluation is made, if the propagation distance is greater than its wavelength in the medium, assuming that it is n times the wavelength in the medium, then n x 2 x pi is added to the phase of the induced electromotive force when solving for the changed phase.

Referring to fig. 12, an embodiment of the present application provides an apparatus for remotely detecting a layer interface position and electromagnetic information, as shown in the figure, the apparatus mainly includes:

And is

As a possible implementation, the eliminating, by the receiving coil, the direct-coupled electromotive force generated by the transmitting coil to the receiving coil according to the model based on the transmitting coil and the receiving coil in the first processing module may include:

As a possible implementation, in the second processing module, the calculating, according to the model of the receiving coil and the transmitting coil, the reflected field of the transmitting coil at the receiving coil by using a mirroring method includes determining a relationship between a mirror source of the transmitting coil and a real source, and the determining a relationship between a mirror source of the transmitting coil and a real source may include:

，

is expressed as

，

Is the wave impedance in the first layer of medium,

is the wave impedance in the second layer of medium, wherein,

，

，

and

and

，

Wherein

And

And

Wherein, in the step (A),

the first operating frequency is the wavelength in vacuum,

、

a wavelength in vacuum for a second operating frequency;

in the equation (1),

in the equation (2),

in the equation (3),

in the formula (I), the compound is shown in the specification,

presentation pair

Taking a real part of the signal,

presentation pair

、

，

，

wherein

，

，

，

，

、

、

and

permeability of first and second layer media respectively，k₁And k₂Propagation constants of electromagnetic waves with first working frequency and electromagnetic waves with second working frequency in the first layer medium respectively are expressed as follows:

and

j is the imaginary unit, j²=-1；

=0.7485 and

The foregoing is considered as illustrative of the preferred embodiments of the invention and the technical principles employed. It will be understood by those skilled in the art that the present application is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the application. Therefore, although the present application has been described in more detail with reference to the above embodiments, the present application is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present application, and the scope of the present application is determined by the scope of the appended claims.

Claims

1. A method for remotely detecting layer interface location and electromagnetic information, the method comprising:

according to the induced electromotive force, by transmitting electromagnetic waves with different working frequencies, the amplitude and the phase angle of the induced electromotive force of the receiving coil under each working frequency are solved, and according to the amplitude and the phase angle of the induced electromotive force, the position and the electromagnetic information of the medium layer interface are solved;

wherein the model of the non-axisymmetrically wound far probe fractional turn receive coil is represented as:

And is

In the formulaiIs shown asiA sector-shaped area is formed by the circular arc-shaped area,n _irepresenting a sector areaiThe number of the corresponding fractional turns is,Nthe number of the sector areas;

wherein, in the calculating the reflected field of the transmitting coil at the receiving coil by adopting the mirror image method according to the models of the receiving coil and the transmitting coil, the determining the relationship between the mirror image source of the transmitting coil and the real source comprises:

，

is expressed as

，

Is the wave impedance in the first layer of medium,

is the wave impedance in the second layer of medium, wherein,

，

，

and

and

，

Wherein

And

the real parts of the dielectric constants of the first layer medium and the second layer medium respectively,

and

the electrical conductivity of the first layer of medium and the second layer of medium respectively,

2. The method of claim 1, wherein the eliminating, from the receive coil, the direct-coupled electromotive force generated by the transmit coil to the receive coil based on the model of the transmit coil and the receive coil comprises:

3. The method of claim 1, wherein the solving for the magnitude and phase angle of the induced electromotive force of the receiving coil at each operating frequency by emitting electromagnetic waves of different operating frequencies based on the induced electromotive force, and the solving for the position and electromagnetic information of the dielectric layer interface based on the magnitude and phase angle of the induced electromotive force comprises:

setting the distance between the layer interface and the transmitting coil as d meters, wherein the electromagnetic information of the medium layer interface comprises the conductivity of the first layer medium

And the electrical conductivity of the second layer medium

；

And

Wherein, in the step (A),

the first operating frequency is the wavelength in vacuum,

、

a wavelength in vacuum for a second operating frequency;

in the equation (1),

in the equation (2),

in the equation (3),

in the formula (I), the compound is shown in the specification,

presentation pair

Taking a real part of the signal,

presentation pair

、

，

wherein

，

，

，

，

Indicating a first operating frequencyThe complex dielectric constant of the first layer of dielectric at a rate,

、

is the real part of the dielectric constant of the first layer medium and the second layer medium,

、

is the electrical conductivity of the first layer of medium and the second layer of medium,

、

and

of a first and second layer of medium respectivelyMagnetic permeability, k₁And k₂Propagation constants of electromagnetic waves with first working frequency and electromagnetic waves with second working frequency in the first layer medium respectively are expressed as follows:

and

j is the imaginary unit, j²=-1；

Solving equations (1) to (3) of the nonlinear equation system by an iterative method to obtain the distance d between the interface of the medium layer and the transmitting coil and the conductivity of the first layer of medium

And the electrical conductivity of the second layer medium

。

4. An apparatus for remotely sensing layer interface position and electromagnetic information, the apparatus comprising:

the fifth processing module is used for solving the amplitude and the phase angle of the induced electromotive force of the receiving coil under each working frequency by transmitting electromagnetic waves with different working frequencies according to the induced electromotive force, and solving the position and the electromagnetic information of the interface of the medium layer according to the amplitude and the phase angle of the induced electromotive force;

And is

in the second processing module, the calculating, according to the models of the receiving coil and the transmitting coil, the reflected field of the transmitting coil at the receiving coil by using a mirror image method includes determining a relationship between a mirror image source of the transmitting coil and a real source, and the determining a relationship between the mirror image source of the transmitting coil and the real source includes:

，

is expressed as

，

Is the wave impedance in the first layer of medium,

is the wave impedance in the second layer of medium, wherein,

，

，

and

and

，

Wherein

And

and

5. The apparatus of claim 4, wherein the model based on the transmit coil and the receive coil in the first processing module for canceling direct-coupled electromotive force generated by the transmit coil to the receive coil according to the receive coil comprises:

6. The apparatus of claim 4, wherein the fifth processing module comprises: