CN108873083B - A kind of artificial field source frequency domain electromagnetism apparent resistivity measurement method - Google Patents
A kind of artificial field source frequency domain electromagnetism apparent resistivity measurement method Download PDFInfo
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Abstract
The invention discloses a kind of artificial field source frequency domain electromagnetism apparent resistivity measurement methods, and first according to detection or exploration demand, horizontal electric dipole field source and electric field level amount measuring system is arranged, the device fixed with reception using transmitting for non-destructive testing.Certain measuring point multifrequency point electromagnetism E is recorded using the electromagnetic signal of different frequency fxComponent.The electromagnetic field E of corresponding frequency point combination is calculated using the approximation method of first-order difference derivationxTo the derivative of frequency pointAnd the local derviation information after calculating is stored.Utilize electromagnetic field ExDerivative of the component to frequency pointCarry out apparent resistivity conversion process.The method overcome the limitations that apparent resistivity solution is carried out using Ka Niya apparent resistivity definition criterion, conventional APPARENT RESISTIVITY is reduced again simultaneously to seek needing in face of Solving Nonlinear Systems of Equations bring calculated result risk of instability, it is effective to improve computation of apparent resistivity efficiency and accuracy.
Description
Technical field
The present invention relates to the artificial field source frequency domain electromagnetism apparent resistivity measurement methods in exploration geophysics field, especially
Place is that the APPARENT RESISTIVITY acquiring method reduces Solving Nonlinear Equation inaccuracy without solving nonlinear equation
Apparent resistivity definition error is brought, traditional computation of apparent resistivity accuracy is improved.
Background technique
In geophysical exploration in order to describe the electric conductivity of underground rock, ore generally use resistivity or conductivity come into
Row narration, however when actually carrying out the work, the comprehensive effect of the underground rock of acquisition, ore, is not the true electricity of underground rock, ore
Resistance rate, is referred to as apparent resistivity, with the Multiple factors phase such as underground rock, the ingredient of ore, structure, acquisition device laying mode
It closes.
Controlled-source audiomagnetotellurics method (abbreviation CSAMT) is the artificial field source electromagnetic sounding method of frequency domain, and this method is adopted
View parameter is calculated with the similar apparent resistivity definition form of magnetotelluric method (abbreviation MT), significantly due to the artificial field source of introducing
Improve observation signal quality.With the continuous development of electromagnetic exploration method, such method be widely used in petroleum, natural gas,
The Exploration Domains such as metallic ore, underground heat, the hydrology, environment.But artificial field source frequency electromagnetic method introduces artificial field source and successfully solves
The observation as caused by the randomness and signal strength of natural source are weak is difficult, but a series of new problems also occurs.For example, it is also
It is to be calculated (such as using conventional Ka Ni Asian TV Station resistivity definition modeOr), it should
The precondition of definition mode is that electromagnetic wave is propagated with plane wave, therefore needs observation area being placed in far field, utilizes far field
Data calculate apparent resistivity, rather than the apparent resistivity that far field calculates can generate Severe distortion, therefore give up transition region and close
The data in area, to reduce the CSAMT scope of application.Meanwhile field need of work far field measure two orthogonal electric fields and
Magnetic field reduces field work efficiency and improves ground observation cost.In addition, conventional APPARENT RESISTIVITY definition mode is adopted
Use E_ExWithIt is solved, this definition mode is applicable in most of measured zone, overcomes the non-planar area cannot to solve view
Resistivity obstacle, but it needs to solve Nonlinear System of Equations to define corresponding apparent resistivity, leads to apparent resistivity
Accuracy relies on the solution of Nonlinear System of Equations, to influence computation of apparent resistivity accuracy and efficiency.
Summary of the invention
It is an object of the invention in order to overcome the problems, such as that background technique describes, while in view of the deficiencies of the prior art, mention
A kind of artificial field source frequency domain electromagnetism apparent resistivity measurement method is supplied, this method avoid the flat of Ka Niya apparent resistivity definition
Surface wave is assumed to require, while reducing conventional APPARENT RESISTIVITY again and seeking needing to calculate in face of Solving Nonlinear Systems of Equations bring
Unstable result risk, it is effective to improve computation of apparent resistivity efficiency.
To realize the above-mentioned technical purpose, the technical solution adopted by the present invention is a kind of artificial field source frequency domain electromagnetism apparent resistance
Rate measurement method, field real data acquisition in use rectangular coordinate system, according to Theory of Electromagnetic Field, the electric field of HORIZONTAL ELECTRIC DIPOLE
Component ExExpression formula under rectangular coordinate system are as follows:
E in formulaxElectric field component on the direction x is expressed as under rectangular coordinate system, and σ is the conductivity of homogeneous half space, and φ is to see
The angle of measuring point and dipole moment positive direction, r are observation point at a distance from dipole moment center, and k is wave number, under the conditions of quasi-static,μ is magnetic conductivity, and the π of ω=2 f is angular frequency, and f is frequency.I indicates virtuality unit.For centre
Variable, I are expressed as the size of electric dipole emission current, and dL is expressed as the length of HORIZONTAL ELECTRIC DIPOLE；
Diagonal frequencies ω seeks local derviation, can obtain:
Abbreviation are as follows:
Wherein, ρ0It is the resistivity of medium.
It enablesP is induction number, and m is plural intermediate variable, therefore, further
Abbreviation are as follows:
Wherein,
Finally, electromagnetism E is obtainedxThe local derviation of diagonal frequencies ω:
Wherein,Modulus can obtain:
Then, the logarithm using e the bottom of as is taken to formula the right and left, and willIt substitutes into, abbreviation can obtain:
Therefore, the electromagnetism E in the direction rectangular coordinate system x is utilizedxApparent resistivity ρ is calculated the derivative of frequency fiIt indicates are as follows:
Therefore, as long as obtaining ExIt can be realized as the calculating of apparent resistivity to the derivative of frequency f, without to nonlinear equation
It solves to define APPARENT RESISTIVITY, effectively raises computation of apparent resistivity accuracy, while improving to underground geologic anomaly
The accuracy of explanation.
A kind of artificial field source frequency domain electromagnetism apparent resistivity measurement method, the steps included are as follows:
Step S1: first according to detection or exploration demand, horizontal electric dipole field source and electric field level component measurement system are set
System, the device fixed with reception using transmitting for non-destructive testing；One emission source multi-measuring point, a plurality of survey line are used for exploration
Observed pattern；Emission source emits multifrequency electromagnetic signal by HORIZONTAL ELECTRIC DIPOLE.
Step S2: the potential difference V between two measuring electrodes, the measuring electrode and confession are recorded using electromagnetic signal receiver
The orientation of electrode is consistent, while the d that the distance between records measuring electrode, using between potential difference V and measuring electrode away from
Ratio from d seeks single frequency point electromagnetism ExThen component records certain measuring point multifrequency point using the electromagnetic signal of different frequency f
Electromagnetism ExComponent.
Step S3: a series of electromagnetism E for the frequencies sought is utilizedxComponent carries out the combination of adjacent frequency, and uses
The approximation method of first-order difference derivation calculates the electromagnetic field E of corresponding frequency point combinationxTo the derivative of frequency pointAnd to calculating
Local derviation information afterwards is stored.
Step S4: electromagnetic field E is utilizedxDerivative of the component to frequency pointApparent resistivity conversion process is carried out, is used
Seek solution's expression are as follows:
Wherein, μ is magnetic conductivity, and r is the distance between dipole moment center and observation point, and the π of ω=2 f is angular frequency, and I is hair
Size of current is penetrated, dL is the length in dipole emission source, ρiIndicate i-th i frequency point apparent resistivity.
Electromagnetic signal receiver refers to for recording the potential difference between two measuring electrodes in step S2.
A kind of artificial field source frequency domain electromagnetism apparent resistivity measurement method provided by the invention, the good effect generated:
(1) present invention fully considers the computation of apparent resistivity of nonplanar wave propagation regions when seeking apparent resistivity, extends
Traditional artificial field source electromagnetic method measurement range, so as to carry out Reconnaissance Survey in nonplanar wave region and far field；
(2) present invention only needs to measure the electromagnetic field signal of multifrequency point simple component, does not need to measure mutually perpendicular electric field
Apparent resistivity is calculated with magnetic field, the strategy that can be realized very well multiple tracks while measure, to the traditional controllable source electromagnetism of reduction
Method field measurement equipment heaviness improves guidance, improves ground observation data acquisition efficiency, reduces ground observation cost；
(3) present invention uses electric field ExComponent defines apparent resistivity to the derivative of frequency, woth no need to according to tradition view electricity
Resistance rate calculation method, the disadvantages of avoiding the solution inaccuracy bring computation of apparent resistivity low precision of nonlinear equation, effectively
Improve apparent resistivity solution efficiency precision.
(4) the apparent resistivity definition method that the present invention calculates is simple, calculates quickly, is very suitable to survey with resistivity for detection
Several nondestructive detecting instruments.
Detailed description of the invention
Fig. 1 is according to a kind of artificial field source frequency domain electromagnetism apparent resistivity measurement method basic procedure provided by the invention
Figure；
Fig. 2 is to be shown according to a kind of artificial field source frequency domain electromagnetism apparent resistivity measurement method field provided by the invention arrangement
It is intended to；
Fig. 3 is according to a kind of artificial field source frequency domain electromagnetism apparent resistivity measurement method theoretical model view provided by the invention
Resistivity calculates as a result, the theoretical model are as follows: three layers of H curve, 100 Ω m of the first layer resistivity of model, thickness 100m, and second
Layer resistivity 25 Ω m, thickness 200m, 100 Ω m of third layer resistivity, thickness are infinitely great；Transmitting-receiving is away from 8000m.
Fig. 4；For according to a kind of artificial field source frequency domain electromagnetism apparent resistivity measurement method theoretical model provided by the invention
Computation of apparent resistivity is as a result, the theoretical model are as follows: three layers of H curve, the first layer resistivity of model 100 Ω m, thickness 100m, the
Two layer resistivities 25 Ω m, thickness 200m, 100 Ω m of third layer resistivity, thickness are infinitely great；Transmitting-receiving away from
Specific embodiment
It is that the present invention is further illustrated in conjunction with the drawings and specific embodiments below
As shown in Figure 1, a kind of artificial field source frequency domain electromagnetism apparent resistivity measurement method provided by the invention comprising with
Lower step:
Step S1: first according to exploration demand, being arranged suitable location of source, and survey area lay a plurality of survey line with
And corresponding observation point, electromagnetic signal receiver is placed at observation point, and location of source is placed in exploration area by signal transmitter
Domain sends the electromagnetic signal of multiple frequencies；
Step S2: the potential difference V between two measuring electrodes, the measuring electrode and confession are recorded using electromagnetic signal receiver
The orientation of electrode is consistent, while the d that the distance between records measuring electrode, using between potential difference V and measuring electrode away from
Ratio from d seeks single frequency point electromagnetism ExThen component records certain measuring point multifrequency point using the current signal of different frequency f
Electromagnetism ExComponent；
Step S3: a series of electromagnetism E for the frequencies sought is utilizedxComponent carries out the combination of adjacent frequency, and uses
The approximation method of first-order difference derivation calculates the electromagnetic field E of corresponding frequency point combinationxTo the derivative of frequency pointAnd to calculating
Derivative information afterwards is stored；
Step S4: electromagnetic field E is utilizedxDerivative of the component to frequency pointApparent resistivity conversion process is carried out, is used
Seek solution's expression are as follows:
Wherein, μ is magnetic conductivity, and r is the distance between dipole moment center and observation point, and the π of ω=2 f is angular frequency, and I is hair
Size of current is penetrated, dL is the length in dipole emission source, ρiiIndicate i-th i frequency point apparent resistivity.
The following are the examples of the present inventor workshop source frequency domain electromagnetism apparent resistivity measurement method.
Theoretical model is three layers of H curve, the first layer resistivity 100 Ω m of theoretical model, thickness 100m, second layer resistance
Rate 25 Ω m, thickness 200m, 100 Ω m of third layer resistivity, thickness are infinitely great；Transmitting-receiving away from respectively 8000m and
Frequency measurement range is 0.1Hz~10KHz.Artificial field source is respectively dipole source, bipolarity source.
Fig. 3 and Fig. 4, which is respectively shown, does not have to transmitting-receiving away from two kinds of artificial field source computation of apparent resistivity results.
Fig. 3 and Fig. 4 compared computation of apparent resistivity result and the whole district provided by the invention view electricity under far zone condition respectively
Resistance rate calculated result.Fig. 3 calculated result show the result under the calculated result that the present invention provides and far zone condition 2Hz~
10KHz has good correspondence, as a result very accurate；Fig. 4's the result shows that, when transmitting-receiving away from farther out when, what the present invention provided
Result under calculated result and far zone condition all has good correspondence in 0.1Hz~10KHz, as a result very accurate.It is above-mentioned
As a result the artificial source whole district frequency domain electromagnetic apparent resistivity measurement method that the present invention provides is also shown in terms of another is
Correctly, while very well the relevant information for indicating subsurface geologic structures avoids iteratively solving traditional APPARENT RESISTIVITY inaccuracy
Bring numerical error has great importance to the accuracy for improving subsurface geology interpretation of anomaly.
Three layers of H-type curve E of Fig. 3 HORIZONTAL ELECTRIC DIPOLEx-fApparent resistivity definition curve (transmitting-receiving is away from 8000m), respectively shows
Dipole source forward modeling and the forward modeling of bipolarity source, far field and APPARENT RESISTIVITY calculated curve and dipole forward modeling use bi-pole source
Mode seeks far field and APPARENT RESISTIVITY curve.
Three layers of H-type curve E of Fig. 4 HORIZONTAL ELECTRIC DIPOLEx-fApparent resistivity definition curve (transmitting-receiving away from), it opens up respectively
Dipole forward modeling and the forward modeling of bipolarity source are shown, far field and APPARENT RESISTIVITY calculated curve and dipole forward modeling are using bipolar
Source mode seeks far field and APPARENT RESISTIVITY curve.
Claims (3)
1. a kind of artificial field source frequency domain electromagnetism apparent resistivity measurement method, it is characterised in that: adopted in the acquisition of field real data
With rectangular coordinate system, according to Theory of Electromagnetic Field, the electric field component E of HORIZONTAL ELECTRIC DIPOLExExpression formula under rectangular coordinate system are as follows:
E in formulaxBe expressed as under rectangular coordinate system electric field component on the direction x, σ is the conductivity of homogeneous half space, φ be observation point with
The angle of dipole moment positive direction, r are observation point at a distance from dipole moment center, and k is wave number, under the conditions of quasi-static,μ is magnetic conductivity, and the π of ω=2 f is angular frequency, and f is frequency；I indicates virtuality unit；For centre
Variable, I are expressed as the size of electric dipole emission current, and dL is expressed as the length of HORIZONTAL ELECTRIC DIPOLE；
Diagonal frequencies ω seeks local derviation, can obtain:
Abbreviation are as follows:
Wherein, ρ0It is the resistivity of medium；
It enablesP is induction number, and m is plural intermediate variable, therefore, further abbreviation
Are as follows:
Wherein,
Finally, electromagnetism E is obtainedxThe local derviation of diagonal frequencies ω:
Wherein,Modulus can obtain:
Then, the logarithm using e the bottom of as is taken to formula the right and left, and willIt substitutes into, abbreviation can obtain:
Therefore, the electromagnetism E in the direction rectangular coordinate system x is utilizedxApparent resistivity ρ is calculated the derivative of frequency fiIt indicates are as follows:
Therefore, as long as obtaining ExIt can be realized as the calculating of apparent resistivity to the derivative of frequency f, without to Solving Nonlinear Equation
To define APPARENT RESISTIVITY, ρiiIndicate i-th i frequency point apparent resistivity.
2. a kind of artificial field source frequency domain electromagnetism apparent resistivity measurement method according to claim 1, it is characterised in that: step
It is rapid as follows,
Step S1: first according to detection or exploration demand, being arranged horizontal electric dipole field source and electric field level amount measuring system, right
In non-destructive testing using transmitting and the device for receiving fixation；Exploration is observed using an emission source multi-measuring point, a plurality of survey line
Mode；Emission source emits multifrequency electromagnetic signal by HORIZONTAL ELECTRIC DIPOLE；
Step S2: the potential difference V between two measuring electrodes, the measuring electrode and power supply electricity are recorded using electromagnetic signal receiver
The orientation of pole is consistent, while the d that the distance between records measuring electrode, utilizes the distance between potential difference V and measuring electrode d's
Ratio seeks single frequency point electromagnetism ExThen component records certain measuring point multifrequency point electromagnetism E using the electromagnetic signal of different frequency fx
Component；
Step S3: a series of electromagnetism E for the frequencies sought is utilizedxComponent carries out the combination of adjacent frequency, and uses a scale
Divide the approximation method of derivation to calculate the electromagnetic field E of corresponding frequency point combinationxTo the derivative of frequency pointAnd to inclined after calculating
Information is led to be stored；
Step S4: electromagnetic field E is utilizedxDerivative of the component to frequency pointCarry out apparent resistivity conversion process, the solution used
Expression formula are as follows:
Wherein, μ is magnetic conductivity, and r is the distance between dipole moment center and observation point, and the π of ω=2 f is angular frequency, and I is transmitting electricity
Size is flowed, dL is the length in dipole emission source, ρiiIndicate i-th i frequency point apparent resistivity.
3. a kind of artificial field source frequency domain electromagnetism apparent resistivity measurement method according to claim 2, it is characterised in that: step
Electromagnetic signal receiver refers to for recording the potential difference between two measuring electrodes in rapid S2.
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| CN109597130A (en) * | 2018-12-21 | 2019-04-09 | 中国地质科学院地球物理地球化学勘查研究所 | A kind of electrical survey method and system |
| CN109917470B (en) * | 2019-04-25 | 2020-06-12 | 中南大学 | Method and device for measuring apparent resistivity of vertical magnetic source wave number |
| CN110927632A (en) * | 2019-09-24 | 2020-03-27 | 新疆万盾能源科技有限责任公司 | Frequency domain horizontal X-direction magnetic field component observation and data processing method |
| CN110703346B (en) * | 2019-11-14 | 2021-06-11 | 张道清 | Same-frequency and same-source ratio measurement method for natural electric field |
| CN110879418B (en) * | 2019-11-28 | 2023-05-23 | 东华理工大学 | Frequency domain electric source electromagnetic field apparent conductivity calculation method |
| CN110989006B (en) * | 2019-12-25 | 2022-07-22 | 中国地质科学院地球物理地球化学勘查研究所 | Static displacement correction method and device in controllable source electromagnetic method measurement and intelligent terminal |
| CN110907999B (en) * | 2019-12-26 | 2021-04-02 | 中南大学 | Active power electrical prospecting method based on passive power electric field signal measurement |
| CN111397589A (en) * | 2020-04-07 | 2020-07-10 | 四川省公路规划勘察设计研究院有限公司 | Deformation monitoring and measuring method |
| CN111694061B (en) * | 2020-05-13 | 2023-06-02 | 东华理工大学 | Multi-dipole source transmitting device applied to electromagnetic exploration |
| CN113309506B (en) * | 2021-05-18 | 2023-02-03 | 山东大学 | Advanced observation method and device based on electric dipole emission in hole |
| CN114076988B (en) * | 2021-10-11 | 2023-02-28 | 中南大学 | Wave number apparent resistivity measuring method based on horizontal electric dipole source |
| CN115437024B (en) * | 2022-11-07 | 2022-12-30 | 四川省冶勘设计集团有限公司 | Artificial source frequency domain electromagnetic field signal of double-parameter processing method of plane wave data |
| CN117741776A (en) * | 2024-02-19 | 2024-03-22 | 山东大学 | Artificial source frequency domain electromagnetic exploration method and system containing natural source reference |
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| CN1252492C (en) * | 2003-12-25 | 2006-04-19 | 周仁安 | Measuring method and instrument for earth electromagnetic wave resistivity |
| CN102183792B (en) * | 2011-03-01 | 2012-07-25 | 吉林大学 | Artificial source frequency domain electromagnetic sounding device and measurement method |
| CN105866844A (en) * | 2016-06-12 | 2016-08-17 | 何继善 | Device and method for measuring whole region measuring current source frequency domain electric field horizontal x component |
| CN106873041B (en) * | 2017-04-19 | 2019-05-31 | 中南大学 | A method of apparent resistivity is obtained by any level electric field component |
| CN107748395B (en) * | 2017-10-19 | 2019-07-02 | 中南大学 | A kind of multifrequency electric resistivity exploration method |
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