CN108169802B - A kind of slow diffusion imaging method of time domain electromagnetic data of harsh media model - Google Patents
A kind of slow diffusion imaging method of time domain electromagnetic data of harsh media model Download PDFInfo
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- CN108169802B CN108169802B CN201810174296.7A CN201810174296A CN108169802B CN 108169802 B CN108169802 B CN 108169802B CN 201810174296 A CN201810174296 A CN 201810174296A CN 108169802 B CN108169802 B CN 108169802B
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Abstract
The present invention relates to a kind of slow diffusion imaging methods of time domain electromagnetic data of harsh media model, it is therefore intended that improves the explanation imaging precision of time domain electromagnetic detection data.The present invention first extracts the space uniform roughness parameter of underground on the basis of obtaining detecting area geologic information；The broad sense apparent conductivity and diffusion depth time-domain expression of even roughness medium are derived again, by defining independent variable, kernel function is indicated using infinite series summation, solves broad sense apparent conductivity, the pulsed magnetic field forward solution of harsh media is derived, then carries out variable difference quotient and solves acquisition generalized diffusion process depth；Broad sense apparent conductivity is carried out to actual measurement electromagnetic data and diffusion depth calculates, finally realizes broad sense apparent conductivity-diffusion depth imaging.For the broad sense apparent conductivity and diffusion depth calculation method of harsh media model of the invention compared with the calculation method of classical homogeneous half space medium, apparent conductivity-depth value improves apparent conductivity-depth explanation imaging precision closer to true value.
Description
Technical field
The present invention relates to a kind of time domain electromagnetic method data of field of geophysical exploration to explain calculation method, is particularly suitable for
Meet the time domain electromagnetic exploitation method of harsh media model in the case of practical geology.
Background technique
In electrical prospecting, apparent conductivity and investigation depth are most important two parameters, and resistivity is that reflection material is led
The physical quantity of electrical property, investigation depth still measure a kind of one of the detectivity main standard of method.APPARENT RESISTIVITY is fixed
Justice is that the transient response inverse function of homogeneous half space is directly sought with numerical method, and the measured data of different operating mode can lead to
It crosses numerical radius or inverting iterative technique solves.It is calculated by the limit (minimum and maximum) investigation depth to electrical prospecting, it can
To learn the detectivity of this method.In actual electrical prospecting, in order to preferably explaining measured data as a result, it is desirable to
The numerical value of apparent conductivity and investigation depth and imaging are calculated, more intuitively shows result.
Practical electrical prospecting data are had been applied at present and explain the method calculated, and computation of apparent resistivity is most widely used
Be APPARENT RESISTIVITY definition mode estimation apparent resistivity value that Spies (1986) propose, investigation depth is most widely used
Nabighian and Macnae (1989) propose diffusion depth calculation formula estimate investigation depth.
Australian Patent 847270G01V003116 discloses ground and is laid with Loop source progress aviation exploration method, on ground
Surface launching transition electromagnetic pulse, aircraft, which carries, receives the electromagnetic field that systematic survey the earth generates, according to amplitude size by believing
Number processing can determine the objective body of prediction.
United States Patent (USP) US5610523 discloses the electromagnetic survey system of a kind of transmitting of land used planar coil, aerospace plane detection
And method, it is handled using the signal that magnetic resistivity analysis and magnetic induced polarization interface differential technique receive, carries out judgement sulphides
The detection method of shape substance.But above data explain calculation method be based on the calculation formula under uniform dielectric theory, and it is real
Border ball medium is influenced during its deposition or diagenesis etc. by differential compaction and metamorphism etc., so that stratum has complexity
Anisotropic property, i.e., practical geologic structure is all harsh media, lead to calculated resistivity value and actually have deviation and
Investigation depth is partially deeper than actual depth, therefore seriously affects the accuracy of later data explanation results, so being directed to practical geology
The data of the undefined harsh media generalized conductivity of situation explain that Research on Calculation is of great significance.
Summary of the invention
It is an object of the invention to explain the deficiency of calculation method for available data, according to being defined in the case of practical geology
Generalized conductivity and diffusion depth definition mode, the time domain electromagnetic method data for providing a kind of harsh media model explain
Calculation method.
Main idea is that: on the basis of APPARENT RESISTIVITY definition mode and diffusion depth definition mode
On, according to the definition of harsh media generalized conductivity, derive harsh media broad sense electricity in the case of being adapted to conform with practical geology
The apparent resistivity formula and diffusion depth formula of conductance calculate broad sense apparent resistivity and diffusion are deep according to roughness parameter
Degree.
The invention is realized in this way a kind of slow diffusion imaging method of time domain electromagnetic data of harsh media model includes:
1) detecting area geologic information is first obtained, the space uniform roughness parameter of underground is obtained according to Given information；
Further, according to the borehole data of search coverage, the rock composition situation of search coverage is known, according to rock section
It manages surface image and Pixel-Covering Method principle obtains fractal dimension D, and then obtain space uniform roughness parameter λ=2-D.
2) electromagnetism measured data is pre-processed, including the superposition of electromagnetic data bipolarity, noise remove and electromagnetism number
According to the processing such as sampling；
3) harsh media generalized conductivity is brought into wave number expression formula, derives the magnetic field expression of underground even roughness medium
Formula, by define independent variable, by kernel function use infinite series summation indicate and for monotone variation form, obtain broad sense view conductance
Rate calculation method carries out broad sense apparent conductivity parameter to pretreated electromagnetic data and calculates；
Further, by harsh media generalized conductivity formula σ=σ0(iω)β, wherein σ is generalized conductivity, σ0It is straight
Galvanic electricity conductance, β are space uniform roughness parameter,ω is angular frequency；It brings into wave number expression formula, k2=-i ω μ σ0
(iω)β, wherein μ is magnetic conductivity, takes vertical electric dipole vertical magnetic field component H tozIn expression formula
Wherein I is emission current, and ds is the length of every section of galvanic couple, and y is the y-coordinate of observation point, and r is transmitting-receiving away from naturally right
Several bottom e ≈ 2.71828；It does s=i ω replacement and calculates inverse Laplace transformation again, obtain the response of step current:
WhereinFor the vertical electric dipole vertical magnetic field time-derivative of step current, α=(μ σ0)1/2R, t are the time；
Fieldwork induced electromotive force VdAre as follows:
Wherein S is the effective area of receiving coil；Its kernel function is
It enablesThe value of α is solved, and then obtains DC conductivity σ0。
4) thought is derived according to the diffusion depth of homogeneous half space model, brings harsh media generalized conductivity formula into one
Diffusion equation in the case of dimension has derived the forward solution of the pulsed magnetic field of underground harsh media, is equal to 0 to z difference quotient and solves broad sense expansion
Depth is dissipated, roughness parameter value is recycled to carry out generalized diffusion process depth calculation；
Further, according to the definition mode of classical diffusion depth, harsh media generalized conductivity formula, one-dimensional feelings are brought into
The forward solution of diffusion equation under condition, pulse magnetic field is
To z difference quotient
Generalized diffusion process depth can be solved by enabling formula (6) to be equal to 0.
5) broad sense apparent conductivity-diffusion depth imaging is carried out.
The utility model has the advantages that compared with prior art, the present invention can calculate harsh media generalized conductivity apparent conductivity and
Diffusion depth, it is consistent with the unusual diffusion theory of harsh media, more meet actual conductivity and depth location, improves view electricity
Conductance-depth cross-section diagram accuracy.This method carries out electromagnetic surveying searching mineral resources for China and provides new technical guarantee,
Be conducive to the functionization of time domain electromagnetic exploitation method.
Detailed description of the invention
Fig. 1 is the slow diffusion imaging method flow chart of time domain electromagnetic data of harsh media model；
Fig. 2 is time domain electromagnetic detection measured data pretreatment process figure；
Fig. 3 is that time domain electromagnetic data calculate apparent conductivity method schematic diagram；
Fig. 4 is the broad sense resistivity-depth effect picture of one embodiment of the invention；
Specific embodiment
In order to make the objectives, technical solutions, and advantages of the present invention clearer, below in conjunction with attached drawing and specific implementation
Mode, the present invention will be described in further detail.One of core of the invention design is that it is wide that invention provides harsh media
The apparent conductivity and diffusion depth calculation method of adopted conductivity, can accurately explain electromagnetic surveying data, to obtain
The relatively accurate information of geologic objective body.It should be appreciated that the specific embodiments described herein are merely illustrative of the present invention, not
For limiting the present invention.
Embodiment
As shown in connection with fig. 1, the slow diffusion imaging method of time domain electromagnetic data of a kind of harsh media model, comprising:
1) detecting area geologic information is first obtained, the space uniform roughness parameter of underground is obtained according to Given information；
In step 1 as shown in Figure 1, according to the borehole data of search coverage, the rock composition situation of search coverage is known,
Fractal dimension D is obtained according to rock joint surface image and Pixel-Covering Method principle, joint plane scan image is inputted and is counted
Calculation machine rejects interference information, according to the principle of projection covering and its information matrix memory module of digital picture two-value figure, figure
It as binaryzation, is covered by minimum box (1x1 pixel), counts required total box number after traversing all submatrixs；Change
Become box to continue to count the sum of different size boxes, until box size is equal to setting value；By gained each group box size with
Box number takes logarithm and is drawn into coordinate, with data point each in least square method Fitting Coordinate System, obtains values of fractal dimension D.Due to sky
Between even roughness degree parameter lambda=2-D, obtain different lithosphere roughness parameters.
2) electromagnetism measured data is pre-processed, including the superposition of electromagnetic data bipolarity, noise remove and electromagnetism number
According to the processing such as sampling；
Since time domain electromagnetic exploration system is during actual measurement, the received electromagnetic data of receiver institute will receive power frequency
The electromagnetic noise interferences such as noise, atmospherics and white noise etc., cause the received electromagnetic data of electromagnetic prospecting system by compared with
For complicated noise jamming.In order to improve the quality of data, the characteristics of according to time domain electromagnetic signal, the data of actual measurement are carried out bipolar
Property superposition removal white noise and random noise, then electromagnetic noise interference is removed by the filtering of adaptive scalar Kalman.
Further, measured data pretreatment process figure as shown in Figure 2.Bipolarity superposition, filtering first are carried out to data, gone
Except noise jamming.Electromagnetic data sampling processing is carried out again, first since determining first sampling road first sampled point
Initial point, sampling interval are calculated at equal intervals by approximate log, and data window width is 100.1(1.26) times relationship；Sampling Integral calculates
Formula are as follows:It according to said method handles until end of data.
3) harsh media generalized conductivity is brought into wave number expression formula, derives the magnetic field expression of underground even roughness medium
Formula, by define independent variable, by kernel function use infinite series summation indicate and for monotone variation form, obtain broad sense view conductance
Rate calculation method carries out broad sense apparent conductivity parameter to pretreated electromagnetic data and calculates；
Shown in Figure 3 and combine Fig. 1, induced electromotive force calculates broad sense apparent conductivity method in step 3.According to eelctric dipole
The analytic solutions of the homogeneous half space of son calculate and solve whole district's apparent conductivity.It comprises the steps of:
A. input measurement point coordinate；
B. transmitting-receiving is calculated away from r；
C. the kernel function of electric dipole response is calculated；
By harsh media generalized conductivity formula (σ=σ0(iω)β, wherein σ is generalized conductivity, σ0For DC conductivity,
β is space uniform roughness parameter,ω is angular frequency), it brings into wave number expression formula, k2=-i ω μ σ0(iω)β
(wherein μ is magnetic conductivity), takes vertical electric dipole vertical magnetic field component H tozIn expression formula
Wherein I is emission current, and ds is the length of every section of galvanic couple, and y is the y-coordinate of observation point, and r is transmitting-receiving away from naturally right
Several bottom e ≈ 2.71828；It does s=i ω replacement and calculates inverse Laplace transformation again, obtain the response of step current:
WhereinFor the vertical electric dipole vertical magnetic field time-derivative of step current, α=(μ σ0)1/2R, t are the time；
Fieldwork induced electromotive force VdAre as follows:
Wherein S is the effective area of receiving coil；Its kernel function is
D. the kernel function f (α) that measured data calculates, determines conductivity value；
It enablesBy carrying out solution value to kernel function come reverse apparent conductivity, view electricity is finally calculated
Conductance
4) thought is derived according to the diffusion depth of homogeneous half space model, brings harsh media generalized conductivity formula into one
Diffusion equation in the case of dimension has derived the forward solution of the pulsed magnetic field of underground harsh media, is equal to 0 to z difference quotient and solves broad sense expansion
Depth is dissipated, roughness parameter value is recycled to carry out generalized diffusion process depth calculation；
According to the definition mode of classical diffusion depth, diffusion equation under one-dimensional case, the forward solution of pulse magnetic field isIt is enabled to be equal to zero to z difference quotient, so that it may which the distance that must be shown up when reaching maximum is as spread
Depth.Bring harsh media generalized conductivity formula, diffusion equation under one-dimensional case into, the forward solution of pulse magnetic field is
To z difference quotient
Generalized diffusion process depth can be solved by enabling formula (6) to be equal to 0.
5) broad sense apparent conductivity-diffusion depth imaging is carried out.
Fig. 4 is the broad sense resistivity-depth effect picture using one embodiment of the invention shown in FIG. 1, as a result meets reality
Example reality is applied, is explained for time domain electromagnetic exploitation method field high-precision and provides new idea and method.
The foregoing is merely illustrative of the preferred embodiments of the present invention, is not intended to limit the invention, all in essence of the invention
Made any modifications, equivalent replacements, and improvements etc., should all be included in the protection scope of the present invention within mind and principle.
Claims (4)
1. a kind of slow diffusion imaging method of time domain electromagnetic data of harsh media model, which comprises the steps of:
1) detecting area geologic information is first obtained, the space uniform roughness parameter of underground is obtained according to Given information；
2) electromagnetism measured data is pre-processed, including the superposition of electromagnetic data bipolarity, noise remove and electromagnetic data take
The processing such as sample；
3) harsh media generalized conductivity is substituted into wave number expression formula, derives the magnetic field expression formula of underground even roughness medium,
By defining independent variable, kernel function is indicated using infinite series summation, broad sense apparent conductivity calculation method is obtained, to pretreatment
Electromagnetic data afterwards carries out broad sense apparent conductivity parameter and calculates；
4) thought is derived according to the diffusion depth of homogeneous half space model, substitutes into harsh media generalized conductivity formula to one-dimensional feelings
Diffusion equation under condition derives the forward solution of the pulsed magnetic field of underground harsh media, is equal to 0 to z difference quotient and solves generalized diffusion process depth,
Roughness parameter value is recycled to carry out generalized diffusion process depth calculation；
5) above-mentioned calculated result broad sense apparent conductivity-diffusion depth is carried out to be imaged.
2. a kind of slow diffusion imaging method of time domain electromagnetic data of harsh media model described in accordance with the claim 1, feature
It is:
In step 1, according to the borehole data of search coverage, the rock composition situation of search coverage is known, according to rock joint table
Face image and Pixel-Covering Method principle obtain fractal dimension D, and then obtain space uniform roughness parameter λ=2-D.
3. a kind of slow diffusion imaging method of time domain electromagnetic data of harsh media model described in accordance with the claim 1, feature
It is:
In step 3, by harsh media generalized conductivity formula σ=σ0(iω)β, wherein σ is generalized conductivity, σ0For DC conductance
Rate, β are space uniform roughness parameter,ω is angular frequency；It substitutes into wave number expression formula, k2=-i ω μ σ0(iω)β,
Wherein μ is magnetic conductivity, takes vertical electric dipole vertical magnetic field component H tozIn expression formula
Wherein I is emission current, and ds is the length of every section of galvanic couple, and y is the y-coordinate of observation point, and r is transmitting-receiving away from natural logrithm
Bottom e ≈ 2.71828；It does s=i ω replacement and calculates inverse Laplace transformation again, obtain the response of step current:
WhereinFor the vertical electric dipole vertical magnetic field time-derivative of step current, α=(μ σ0)1/2R, t are the time；Field is real
Survey induced electromotive force VdAre as follows:
Wherein S is the effective area of receiving coil；Its kernel function is
It enablesThe value of α is solved, and then obtains DC conductivity σ0。
4. a kind of slow diffusion imaging method of time domain electromagnetic data of harsh media model described in accordance with the claim 1, feature
It is:
In step 4, according to the definition mode of classical diffusion depth, harsh media generalized conductivity formula is substituted into, under one-dimensional case
The forward solution of diffusion equation, pulse magnetic field is
To z difference quotient
Generalized diffusion process depth can be solved by enabling formula (6) to be equal to 0.
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| CN110135022B (en) * | 2019-04-28 | 2022-10-14 | 吉林大学 | Generalized skin depth calculation method based on polarized medium model |
| CN112526621B (en) * | 2020-12-15 | 2021-10-22 | 吉林大学 | Ground-air electromagnetic data slow diffusion multi-parameter extraction method based on neural network |
| CN112666618B (en) * | 2020-12-16 | 2022-04-19 | 吉林大学 | Geometric-physical property multi-characteristic parameter extraction method for multi-phase medium |
| CN113406709B (en) * | 2021-07-23 | 2022-05-31 | 吉林大学 | Ground-air electromagnetic data retrieval method based on high-generalization neural network |
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| CN105044793A (en) * | 2015-06-17 | 2015-11-11 | 中国科学院地质与地球物理研究所 | Inversion method and apparatus for multi-channel transient electromagnetic detection data |
| CN107292100A (en) * | 2017-06-15 | 2017-10-24 | 内蒙古科技大学 | A kind of computational methods of rock structural face fractal dimension |
| CN107305600A (en) * | 2016-04-21 | 2017-10-31 | 新疆维吾尔自治区煤炭科学研究所 | Least square method resistivity three-dimensional approximate inversion technology |
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| CN105044793A (en) * | 2015-06-17 | 2015-11-11 | 中国科学院地质与地球物理研究所 | Inversion method and apparatus for multi-channel transient electromagnetic detection data |
| CN107305600A (en) * | 2016-04-21 | 2017-10-31 | 新疆维吾尔自治区煤炭科学研究所 | Least square method resistivity three-dimensional approximate inversion technology |
| CN107292100A (en) * | 2017-06-15 | 2017-10-24 | 内蒙古科技大学 | A kind of computational methods of rock structural face fractal dimension |
Non-Patent Citations (1)
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| "电导率连续变化大地电磁无网格法数值模拟";黄廷哲 等;《湖南大学学报（自然科学版）》;20170831;第44卷(第8期);第91-99页 |
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