CN104375197A - Electromagnetic detection method and device - Google Patents

Abstract

The embodiment of the invention discloses an electromagnetic detection method and device. The electromagnetic detection method includes the steps of obtaining the information and the maximum detection depth of a detected region; determining calculation parameters including the transmitting source length, the minimum receiving and transmitting distance, the time domain transmitted waveform and the frequency domain transmitted waveform according to the maximum detection depth; detecting the detected region according to the determined calculation parameters, and obtaining detection information data; calculating the time domain signal to noise ratio factor of the detection information data, and judging the effectiveness of the detection information data according to the time domain signal to noise ratio factor; calculating the time domain equivalent apparent resistivity, the frequency domain equivalent apparent resistivity, the apparent charging rate of time domain electric field information and the amplitude polarization coefficient of frequency domain electromagnetic field information of the detected region according to the detection information data with the effective judgment result. By means of the electromagnetic detection method and device, it can be guaranteed that the information with strong signals is obtained, and the construction efficiency can be improved.

Description

A kind of electromagnetic exploration method and device

Technical field

The present invention relates to technical field of geophysical exploration, particularly relate to a kind of electromagnetic exploration method and device.

Background technology

Magneto-electrotelluric exploration is the important method of exploration of one in geophysical survey, in oil-gas exploration, geothermal prospecting, macrotectonics exploration and the earth's crust, volcano and seismic study, have important application.By electromagnetic surveying technology, scout can obtain orthogonally waiting electromagnetism and magnetic field, and the formation characteristics parameter such as apparent resistivity, thus infers the information such as position such as stratum equal thickness and hydrocarbon targets.

Time-frequency electromagnetic method adopts more a kind of electromagnetic exploration method at present.Described time-frequency electromagnetic method mainly comprises: adopt a large horizontal long lead source to excite the square wave of different frequency on ground, the survey line being parallel to emissive source on ground receives electric field information and Magnetic Field, then calculates the apparent resistivity on stratum according to described electric field information and Magnetic Field.

Realizing in the application's process, inventor finds that in prior art, at least there are the following problems: existing time-frequency electromagnetic method is applicable to emissive source and observes to far field more greatly to distance to survey line, arrive region more greatly for stake resistance, the information signal collected is very weak, have impact on the efficiency of construction.

Summary of the invention

The object of the embodiment of the present application is to provide a kind of electromagnetic exploration method and device, to ensure to collect the stronger information of signal, improves operating efficiency.

For solving the problems of the technologies described above, the embodiment of the present application provides a kind of electromagnetic exploration method and device to be achieved in that

A kind of electromagnetic exploration method, comprising:

Obtain search coverage information and max survey depth;

Determine to comprise emissive source length, minimum transmitting-receiving apart from the calculating parameter of, time domain transmitted waveform and frequency domain transmission waveform according to described max survey depth;

According to the described calculating parameter determined, described search coverage is detected, obtain detection information data;

Calculate the time domain signal to noise ratio (S/N ratio) factor of described detection information data, judge the validity of described detection information data according to the described time domain signal to noise ratio (S/N ratio) factor;

Be effective detection information data according to described judged result, calculate the amplitude polarization coefficient of search coverage time domain and the equivalent apparent resistivity of frequency domain, the apparent chargeability of time domain electric field information and domain electromagnetic field information.

In preferred embodiment, describedly determine minimum transmitting-receiving distance according to max survey depth, comprising: described minimum transmitting-receiving is apart from being more than or equal to max survey depth.

In preferred embodiment, described according to max survey depth determination emissive source length, comprising: described emissive source length is less than or equal to 1/3rd of minimum transmitting-receiving distance.

In preferred embodiment, described time domain transmitted waveform is the square-wave signal of zero passage, comprises and adopts following square-wave signal:

Wherein, A represents the absolute value of amplitude; T indication cycle, n is integer.

In preferred embodiment, described zero passage sends out square-wave signal, and cycle value is:

$T=\left\{\begin{array}{cc}40s& H_{\max }\≤4000m\\ 80s& H_{\max }>4000m\end{array}\right.$

Wherein, H _maxrepresent max survey depth; M is the unit of max survey depth, rice; S is chronomere, second; T indication cycle.

In preferred embodiment, the time domain signal to noise ratio (S/N ratio) factor of described calculating detection information data, comprising: calculate the time domain electric field signal to noise ratio (S/N ratio) Summing Factor time domain magnetic field signal to noise ratio (S/N ratio) factor;

The described time domain electric field signal to noise ratio (S/N ratio) factor adopts following formulae discovery to obtain:

$Q_E\left(T\right)=\frac{{\mathrm{\Σ}}_1^{2N}{E}_x(T,t_i)}{{\mathrm{\Σ}}_1^{2N}\left|E_x(T,t_i)\right|+{\mathrm{\Σ}}_1^{2N}{E}_x(T,t_i)}$

In above formula, Q _e(T) the electric field signal to noise ratio (S/N ratio) factor to be asked is represented; E _x(T, t _i) represent that the transmitting cycle recorded is that the square-wave signal of T is in t electric field signal intensity; N represents the total number of samples in one-period;

The described time domain magnetic field signal to noise ratio (S/N ratio) factor adopts following formula to obtain:

$Q_H\left(T\right)=\frac{{\mathrm{\Σ}}_1^{2N}{B}_z(T,t_i)}{{\mathrm{\Σ}}_1^{2N}\left|B_z(T,t_i)\right|+{\mathrm{\Σ}}_1^{2N}{B}_z(T,t_i)}$

In above formula, Q _h(T) the magnetic field signal to noise ratio (S/N ratio) factor to be asked is represented; B _z(T, t _i) represent that the cycle recorded is that the square-wave signal of T is in t field signal intensity; N represents the total number of samples in one-period.

In preferred embodiment, judge the validity of described detection information data according to the described time domain signal to noise ratio (S/N ratio) factor, comprising:

The described electric field signal to noise ratio (S/N ratio) factor is less than the first preset value, and the described magnetic field signal to noise ratio (S/N ratio) factor is less than the second preset value, and described detection information data are effective.

In preferred embodiment, described first preset value value is 0.05, and described second preset value value is 0.1.

In preferred embodiment, described calculating search coverage time-domain equivalent apparent resistivity is calculated by following formula and obtains:

$E_x\left(t\right)=\frac{\mathrm{I\ρ}}{2\mathrm{\π}}\underset{-l}{\overset{l}{\∫}}(\mathrm{\Φ}\left({\mathrm{\μ}}_0\right)-\frac{2u}{\sqrt{\mathrm{\π}}}{e}^{-u^2})\frac{1}{r^3}\mathrm{d\ζ}$

${\mathrm{dB}}_Z\left(t\right)/\mathrm{dt}=\frac{3\mathrm{I\ρ}}{2\mathrm{\π}}\underset{-l}{\overset{l}{\∫}}(\mathrm{\Φ}\left({\mathrm{\μ}}_0\right)-\sqrt{\frac{2}{\mathrm{\π}}}{e}^{-u^2/2}u(1+u^2/3))\frac{\sin \mathrm{\θ}}{r^4}\mathrm{d\ζ}$

In above formula, $u=\frac{r}{2}\sqrt{\frac{\mathrm{\μ}}{\mathrm{\ρt}}},\mathrm{\Φ}\left(x\right)=\frac{2}{\sqrt{\mathrm{\π}}}{\∫}_0^x{e}^{-{\mathrm{\λ}}^2}\mathrm{d\λ}$

Wherein, ρ represents equivalent apparent resistivity; L is 1/2nd of emissive source length; λ and ζ represents integration variable; I represents electric current; R represents the distance of measuring point to emissive source mid point; T represents the time; μ ₀represent the magnetic permeability in vacuum, μ ₀=4 π 10 ^-7; θ is the angle between emissive source and measuring point.

In preferred embodiment, described calculating search coverage frequency domain equivalence apparent resistivity is calculated by following formula and obtains:

$E_x\left(\mathrm{\ω}\right)=-\frac{\mathrm{I\ρ}}{2\mathrm{\π}}\{\frac{l+x}{{r_1}^3}+\frac{l-x}{{r_2}^3}+\underset{-l}{\overset{l}{\∫}}\frac{1-(1+k_{1}r)e^{-k_{1}r}}{r^3}\mathrm{d\ζ}\}$

${\mathrm{dB}}_Z\left(\mathrm{\ω}\right)=2\mathrm{Iy\ρ}\underset{-l}{\overset{l}{\∫}}\frac{3-(3+3k_{1}r+{k_1}^2{r}^2)e^{-k_{1}r}}{r^5}\mathrm{d\ζ}$

In above formula,

$r=\sqrt{{(\mathrm{\ζ}-x)}^2+y^2},$

$r_1=\sqrt{{(l+x)}^2+y^2},$

$r_2=\sqrt{{(l-x)}^2+y^2},$

$k_1=\sqrt{-\mathrm{i\ω}{\mathrm{\μ}}_0/\mathrm{\ρ}},$

Wherein, ρ represents equivalent apparent resistivity; L is 1/2nd of emissive source length; ζ represents integration variable; X and y is the coordinate of measuring point; ω is angular frequency; μ ₀represent the magnetic permeability in vacuum, μ ₀=4 π 10 ^-7.

In preferred embodiment, the apparent chargeability of the time domain electric field information of described calculating search coverage, comprising:

$M_S\left(t\right)={\∫}_{-\mathrm{\Δt}}^{\mathrm{\Δt}}\frac{\mathrm{\Δ}{V}_2\left(t\right)}{\mathrm{\Δ}{V}_{1+2}\left(t\right)}\mathrm{dt}$

Wherein, M _st () is apparent chargeability to be asked; V ₂t () represents the secondary field of t, V ₁₊₂t () is t resultant field, Δ t is time window, and the span of described Δ t is: be less than four/one-period.

In preferred embodiment, the amplitude polarization coefficient of described calculating search coverage domain electromagnetic field information, adopts following formula to realize:

$P_{\mathrm{FE}}=\frac{A_L-A_H}{A_L}\·100\%$

In above formula, P _fErepresent amplitude polarization coefficient to be asked; A _lrepresent the amplitude of low frequency signal; A _hrepresent the amplitude of high-frequency signal.

A kind of electromagnetic exploration apparatus, comprising: information acquisition unit, calculating parameter determining unit, detection data unit, signal to noise ratio (S/N ratio) factor unit and result computing unit; Wherein,

Information acquisition unit, for obtaining search coverage information and max survey depth;

Calculating parameter determining unit, for determining to comprise emissive source length, minimum transmitting-receiving apart from the calculating parameter of, time domain transmitted waveform and frequency domain transmission waveform according to described max survey depth;

Detection data unit, for detecting described search coverage according to the described calculating parameter determined, obtains detection information data;

Signal to noise ratio (S/N ratio) factor unit, for calculating the time domain signal to noise ratio (S/N ratio) factor of described detection information data, judges the validity of described detection information data according to the described time domain signal to noise ratio (S/N ratio) factor;

Result computing unit, for being effective detection information data according to described judged result, calculates the amplitude polarization coefficient of search coverage time domain and the equivalent apparent resistivity of frequency domain, the apparent chargeability of time domain electric field information and domain electromagnetic field information.

The technical scheme provided from above the embodiment of the present application, electromagnetic exploration method disclosed in the embodiment of the present application and device, by the value of setting transmitting-receiving distance, can reduce the distance of receiver and emissive source, ensure that the signal intensity that receiver receives is comparatively strong, thus improve operating efficiency.Further, adopt the square-wave signal of zero passage can ensure that the primary field that emissive source produces and secondary field are directly separated, the convenient data to gathering are further processed.

Accompanying drawing explanation

In order to be illustrated more clearly in the embodiment of the present application or technical scheme of the prior art, be briefly described to the accompanying drawing used required in embodiment or description of the prior art below, apparently, the accompanying drawing that the following describes is only some embodiments recorded in the application, for those of ordinary skill in the art, under the prerequisite not paying creative work, other accompanying drawing can also be obtained according to these accompanying drawings.

Fig. 1 is the process flow diagram of the application's electromagnetic exploration method embodiment;

Fig. 2 is a kind of time domain zero passage square wave schematic diagram in the application's electromagnetic exploration method embodiment;

Fig. 3 is a kind of frequency domain non-zero passage square wave schematic diagram in the application's electromagnetic exploration method embodiment;

Fig. 4 is the module map of the application's electromagnetic exploration apparatus embodiment.

Embodiment

The embodiment of the present application provides a kind of electromagnetic exploration method and device.

Technical scheme in the application is understood better in order to make those skilled in the art person, below in conjunction with the accompanying drawing in the embodiment of the present application, technical scheme in the embodiment of the present application is clearly and completely described, obviously, described embodiment is only some embodiments of the present application, instead of whole embodiments.Based on the embodiment in the application, those of ordinary skill in the art are not making the every other embodiment obtained under creative work prerequisite, all should belong to the scope of the application's protection.

Fig. 1 is the process flow diagram of a kind of electromagnetic exploration method embodiment of the application.As shown in Figure 1, described electromagnetic exploration method can comprise:

S101: obtain search coverage information and max survey depth.

Obtain search coverage information and max survey depth.Max survey depth can be a known quantity.Described search coverage information can comprise: the information such as search coverage area, search coverage place.According to the information of detection search coverage, observation program can be determined.Described observation program can comprise: adopt horizontal long lead source as emissive source, and survey line can parallel with described horizontal long lead.Above-mentioned long lead source can comprise two electrode A, B.Described survey line can gather the electric field component value parallel with described horizontal long lead source, and the magnetic-field component value vertical with described horizontal long lead source.

S102: determine to comprise emissive source length, minimum transmitting-receiving apart from the calculating parameter of, time domain transmitted waveform and frequency domain transmission waveform according to described max survey depth.

According to described max survey depth, calculating parameter can be determined.Described calculating parameter may be used for the process of electromagnetic surveying data.Described calculating parameter can comprise: emissive source length, minimum transmitting-receiving distance, time domain transmitted waveform and frequency domain transmission waveform.Particularly,

Described minimum transmitting-receiving is apart from meeting:

R _offset≥H _max～6H _max(1)

Described emissive source length can meet:

$\mathrm{AB}\≤(\frac{1}{3}~\frac{1}{5})R_{\mathrm{offset}}---\left(2\right)$

In formula (1) and formula (2), R _offsetrepresent the minor increment in survey line range transmission source; H _maxrepresent max survey depth, AB represents emissive source length.A and B can be respectively used to expression two ground-electrodes, and described emissive source length can represent the distance between two ground-electrodes A, B.

By the value of setting transmitting-receiving distance, the distance of receiver and emissive source can be reduced, ensure that the signal intensity that receiver receives is comparatively strong, thus improve operating efficiency.

The transmitted waveform of described time domain, can choose the square-wave signal of zero passage.Fig. 2 shows a kind of time domain zero passage square wave schematic diagram in the application's electromagnetic exploration method embodiment.

The zero passage square-wave signal of described time domain can adopt following square-wave signal:

Wherein, A represents the absolute value of amplitude; T indication cycle, n is integer.

By adopting the square-wave signal of zero passage, can ensure that the primary field that emissive source produces and secondary field are directly separated, the convenient data to gathering are further processed.

In formula (3), choosing of cycle T can be chosen according to following rule:

$T=\left\{\begin{array}{cc}40s& H_{\max }\≤4000m\\ 80s& H_{\max }>4000m\end{array}\right.---\left(4\right)$

The transmitted waveform of described frequency field, can adopt the square-wave signal of non-zero passage.The square-wave signal of described non-zero passage, the scope of launching the cycle can comprise: 2 ^-8~ 2 ⁸s.Fig. 3 shows a kind of frequency domain non-zero passage square wave schematic diagram in the application's electromagnetic exploration method embodiment.

The square wave information of described non-zero passage, can be more than the multiplicity of ground channel in the multiplicity of high band.Described high frequency generally can refer to that frequency is greater than more than 1 hertz.

S103: detect described search coverage according to the described calculating parameter determined, obtains detection information data.

According to the described calculating parameter determined, can detect described search coverage, obtain the detection information data of described search coverage.The detection information of described search coverage can comprise: the electric field signal strength information of search coverage, the field signal strength information of search coverage.

S104: the time domain signal to noise ratio (S/N ratio) factor calculating described detection information data, judges the validity of described detection information data according to the described time domain signal to noise ratio (S/N ratio) factor.

The time domain signal to noise ratio (S/N ratio) factor of described detection information data can be calculated, the described time domain signal to noise ratio (S/N ratio) factor, the time domain electric field to-noise ratio Summing Factor time domain magnetic field signal to noise ratio (S/N ratio) factor can be comprised.

The described time domain electric field signal to noise ratio (S/N ratio) factor can adopt following formulae discovery to obtain:

$Q_E\left(T\right)=\frac{{\mathrm{\Σ}}_1^{2N}{E}_x(T,t_i)}{{\mathrm{\Σ}}_1^{2N}\left|E_x(T,t_i)\right|+{\mathrm{\Σ}}_1^{2N}{E}_x(T,t_i)}---\left(5\right)$

In formula (5), Q _e(T) the electric field signal to noise ratio (S/N ratio) factor to be asked is represented; E _x(T, t _i) represent that the transmitting cycle recorded is that the square-wave signal of T is in t electric field signal intensity; N represents the total number of samples in one-period;

The described time domain magnetic field signal to noise ratio (S/N ratio) factor can adopt following formula to obtain:

$Q_H\left(T\right)=\frac{{\mathrm{\Σ}}_1^{2N}{B}_z(T,t_i)}{{\mathrm{\Σ}}_1^{2N}\left|B_z(T,t_i)\right|+{\mathrm{\Σ}}_1^{2N}{B}_z(T,t_i)}---\left(6\right)$

In formula (6), Q _h(T) the magnetic field signal to noise ratio (S/N ratio) factor to be asked is represented; B _z(T, t _i) represent that the cycle recorded is that the square-wave signal of T is in t field signal intensity; N represents the total number of samples in one-period.

The validity of described detection information data can be judged according to the described time domain signal to noise ratio (S/N ratio) factor, comprising: the described electric field signal to noise ratio (S/N ratio) factor is less than the first preset value and the described magnetic field signal to noise ratio (S/N ratio) factor is less than the second preset value, and detection information data can be effective.Wherein, described first preset value can value be 0.05, and the value of described second preset value can be 0.1.

S105: be effective detection information data according to described judged result, calculates the amplitude polarization coefficient of search coverage time domain and the equivalent apparent resistivity of frequency domain, the apparent chargeability of time domain electric field information and domain electromagnetic field information.

Be effective detection information data according to described judged result, the amplitude polarization coefficient of the equivalent apparent resistivity of time domain and frequency domain in described search coverage, the apparent chargeability of time domain electric field information and domain electromagnetic field information can be calculated.Particularly:

Described calculating search coverage time-domain equivalent apparent resistivity, can be calculated by following formula and realize:

$E_x\left(t\right)=\frac{\mathrm{I\ρ}}{2\mathrm{\π}}{\∫}_{-l}^l(\mathrm{\Φ}\left({\mathrm{\μ}}_0\right)-\frac{2u}{\sqrt{\mathrm{\π}}}{e}^{-u^2})\frac{1}{r^3}\mathrm{d\ζ}---\left(7\right)$

${\mathrm{dB}}_Z\left(t\right)/\mathrm{dt}=\frac{3\mathrm{I\ρ}}{2\mathrm{\π}}{\∫}_{-l}^l(\mathrm{\Φ}\left({\mathrm{\μ}}_0\right)-\sqrt{\frac{2}{\mathrm{\π}}}{e}^{-u^2/2}u(1+u^2/3))\frac{\sin \mathrm{\θ}}{r^4}\mathrm{d\ζ}---\left(8\right)$

In above formula, $u=\frac{r}{2}\sqrt{\frac{\mathrm{\μ}}{\mathrm{\ρt}}},\mathrm{\Φ}\left(x\right)=\frac{2}{\sqrt{\mathrm{\π}}}{\∫}_0^x{e}^{-{\mathrm{\λ}}^2}\mathrm{d\λ}$

Formula (7)-(8), ρ represents equivalent apparent resistivity; L is 1/2nd of emissive source length; λ and ζ represents integration variable; I represents electric current; R represents the distance of measuring point to emissive source mid point; T represents the time; μ ₀represent the magnetic permeability in vacuum, μ ₀=4 π 10 ^-7; θ is the angle between emissive source and measuring point.

Described calculating search coverage frequency domain equivalence apparent resistivity, can be calculated by following formula and realize:

$E_x\left(\mathrm{\ω}\right)=-\frac{\mathrm{I\ρ}}{2\mathrm{\π}}\{\frac{l+x}{{r_1}^3}+\frac{l-x}{{r_2}^3}+{\∫}_{-l}^l\frac{1-(1+k_{1}r)e^{-k_{1}r}}{r^3}\mathrm{d\ζ}\}---\left(9\right)$

${\mathrm{dB}}_Z\left(\mathrm{\ω}\right)=2\mathrm{Iy\ρ}{\∫}_{-l}^l\frac{3-(3+3k_{1}r+{k_1}^2{r}^2)e^{-k_{1}r}}{r^5}\mathrm{d\ζ}---\left(10\right)$

In above formula,

$r=\sqrt{{(\mathrm{\ζ}-x)}^2+y^2},$

$r_1=\sqrt{{(l+x)}^2+y^2},$

$r_2=\sqrt{{(l-x)}^2+y^2},$

$k_1=\sqrt{-\mathrm{i\ω}{\mathrm{\μ}}_0/\mathrm{\ρ}},$

Formula (9)-(10), ρ represents equivalent apparent resistivity; L is 1/2nd of emissive source length; ζ represents integration variable; X and y is the coordinate of measuring point; ω is angular frequency; μ ₀represent the magnetic permeability in vacuum, μ ₀=4 π 10 ^-7.

The apparent chargeability of the time domain electric field information of described calculating search coverage, can adopt following formula:

$M_S\left(t\right)={\∫}_{-\mathrm{\Δt}}^{\mathrm{\Δt}}\frac{\mathrm{\Δ}{V}_2\left(t\right)}{\mathrm{\Δ}{V}_{1+2}\left(t\right)}\mathrm{dt}---\left(11\right)$

In formula (11), M _st () is apparent chargeability to be asked; V ₂t () represents the secondary electrical field of t, V ₁₊₂t () is t total electric field, Δ t is time window, and the span of described Δ t is: be less than four/one-period.

The amplitude polarization coefficient of described search coverage domain electromagnetic field information can adopt following formulae discovery to obtain:

$P_{\mathrm{FE}}=\frac{A_L-A_H}{A_L}\·100\%---\left(12\right)$

In formula (12), P _fErepresent amplitude polarization coefficient to be asked; A _lrepresent the amplitude of low frequency signal; A _hrepresent the amplitude of high-frequency signal.

By above-mentioned calculating, the information that electromagnetic exploration method will obtain can be obtained.In above-mentioned computation process, consider the angle between the source of penetrating and measuring point, can ensure that the value of the equivalent apparent resistivity obtained is more accurate.Further, not only acquire the data message of frequency domain, the data message of time domain can also be obtained, for follow-up data processing provides more data volume.

Electromagnetic exploration method disclosed in above-described embodiment, by the value of setting transmitting-receiving distance, can reduce the distance of receiver and emissive source, ensures that the signal intensity that receiver receives is comparatively strong, thus improves operating efficiency.

Further, adopt the square-wave signal of zero passage can ensure that the primary field that emissive source produces and secondary field are directly separated, the convenient data to gathering are further processed.

Introduce the electromagnetic exploration apparatus of the application below.

Fig. 4 is the module map of the application's electromagnetic exploration apparatus embodiment.As shown in Figure 4, described device can comprise: information acquisition unit 401, calculating parameter determining unit 402, detection data unit 403, signal to noise ratio (S/N ratio) factor unit 404 and result computing unit 405.Wherein,

Described information acquisition unit 401, may be used for obtaining search coverage information and max survey depth;

Described calculating parameter determining unit 402, may be used for determining to comprise emissive source length, minimum transmitting-receiving apart from the calculating parameter of, time domain transmitted waveform and frequency domain transmission waveform according to described max survey depth;

Described detection data unit 403, may be used for detecting described search coverage according to the described calculating parameter determined, obtains detection information data;

Described signal to noise ratio (S/N ratio) factor unit 404, may be used for the time domain signal to noise ratio (S/N ratio) factor calculating described detection information data, judges the validity of described detection information data according to the described time domain signal to noise ratio (S/N ratio) factor;

Described result computing unit 405, may be used for according to described judged result is effective detection information data, calculates the amplitude polarization coefficient of search coverage time domain and the equivalent apparent resistivity of frequency domain, the apparent chargeability of time domain electric field information and domain electromagnetic field information.

Electromagnetic exploration apparatus embodiment disclosed in above-described embodiment is corresponding with the application's electromagnetic exploration method embodiment, can realize the technique effect of the application's embodiment of the method.

Each embodiment in this instructions all adopts the mode of going forward one by one to describe, between each embodiment identical similar part mutually see, what each embodiment stressed is the difference with other embodiments.Especially, for device embodiment, because it is substantially similar to embodiment of the method, so description is fairly simple, relevant part illustrates see the part of embodiment of the method.

Although depict the application by embodiment, those of ordinary skill in the art know, the application has many distortion and change and do not depart from the spirit of the application, and the claim appended by wishing comprises these distortion and change and do not depart from the spirit of the application.

Claims (13)

1. an electromagnetic exploration method, is characterized in that, comprising:

Obtain search coverage information and max survey depth;

Determine to comprise emissive source length, minimum transmitting-receiving apart from the calculating parameter of, time domain transmitted waveform and frequency domain transmission waveform according to described max survey depth;

According to the described calculating parameter determined, described search coverage is detected, obtain detection information data;

Calculate the time domain signal to noise ratio (S/N ratio) factor of described detection information data, judge the validity of described detection information data according to the described time domain signal to noise ratio (S/N ratio) factor;

Be effective detection information data according to described judged result, calculate the amplitude polarization coefficient of search coverage time domain and the equivalent apparent resistivity of frequency domain, the apparent chargeability of time domain electric field information and domain electromagnetic field information.

2. a kind of electromagnetic exploration method as claimed in claim 1, is characterized in that, describedly determines minimum transmitting-receiving distance according to max survey depth, comprising: described minimum transmitting-receiving is apart from being more than or equal to max survey depth.

3. a kind of electromagnetic exploration method as claimed in claim 2, is characterized in that, described according to max survey depth determination emissive source length, comprising: described emissive source length is less than or equal to 1/3rd of minimum transmitting-receiving distance.

4. a kind of electromagnetic exploration method as claimed in claim 1, is characterized in that, described time domain transmitted waveform is the square-wave signal of zero passage, comprises and adopts following square-wave signal:

Wherein, A represents the absolute value of amplitude; T indication cycle, n is integer.

5. a kind of electromagnetic exploration method as claimed in claim 4, is characterized in that, described zero passage sends out square-wave signal, and cycle value is:

$T=\left\{\begin{array}{cc}40s& H_{\max }\≤4000m\\ 80s& H_{\max }>4000m\end{array}\right.$

Wherein, H _maxrepresent max survey depth; M is the unit of max survey depth, rice; S is chronomere, second; T indication cycle.

6. a kind of electromagnetic exploration method as claimed in claim 1, is characterized in that, the time domain signal to noise ratio (S/N ratio) factor of described calculating detection information data, comprising: calculate the time domain electric field signal to noise ratio (S/N ratio) Summing Factor time domain magnetic field signal to noise ratio (S/N ratio) factor;

The described time domain electric field signal to noise ratio (S/N ratio) factor adopts following formulae discovery to obtain:

$Q_E\left(T\right)=\frac{{\mathrm{\Σ}}_1^{2N}{E}_x(T,t_i)}{{\mathrm{\Σ}}_1^{2N}\left|E_x(T,t_i)\right|+{\mathrm{\Σ}}_1^{2N}{E}_x(T,t_i)}$

In above formula, Q _e(T) the electric field signal to noise ratio (S/N ratio) factor to be asked is represented; E _x(T, t _i) represent that the transmitting cycle recorded is that the square-wave signal of T is in t electric field signal intensity; N represents the total number of samples in one-period;

The described time domain magnetic field signal to noise ratio (S/N ratio) factor adopts following formula to obtain:

$Q_H\left(T\right)=\frac{{\mathrm{\Σ}}_1^{2N}{B}_z(T,t_i)}{{\mathrm{\Σ}}_1^{2N}\left|B_z(T,t_i)\right|+{\mathrm{\Σ}}_1^{2N}{B}_z(T,t_i)}$

In above formula, Q _h(T) the magnetic field signal to noise ratio (S/N ratio) factor to be asked is represented; B _z(T, t _i) represent that the cycle recorded is that the square-wave signal of T is in t field signal intensity; N represents the total number of samples in one-period.

7. a kind of electromagnetic exploration method as claimed in claim 1, is characterized in that, judges the validity of described detection information data, comprising according to the described time domain signal to noise ratio (S/N ratio) factor:

The described electric field signal to noise ratio (S/N ratio) factor is less than the first preset value, and the described magnetic field signal to noise ratio (S/N ratio) factor is less than the second preset value, and described detection information data are effective.

8. a kind of electromagnetic exploration method as claimed in claim 7, is characterized in that, described first preset value value is 0.05, and described second preset value value is 0.1.

9. a kind of electromagnetic exploration method as claimed in claim 1, is characterized in that, described calculating search coverage time-domain equivalent apparent resistivity is calculated by following formula and obtains:

$E_x\left(t\right)=\frac{\mathrm{I\ρ}}{2\mathrm{\π}}\underset{-l}{\overset{l}{\∫}}(\mathrm{\Φ}\left({\mathrm{\μ}}_0\right)-\frac{2u}{\sqrt{\mathrm{\π}}}{e}^{-u^2})\frac{1}{r^3}\mathrm{d\ζ}$

$d{B}_z\left(t\right)/\mathrm{dt}=\frac{3\mathrm{I\ρ}}{2\mathrm{\π}}\underset{-l}{\overset{l}{\∫}}(\mathrm{\Φ}\left({\mathrm{\μ}}_0\right)-\sqrt{\frac{2}{\mathrm{\π}}}{e}^{-u^2/2}u(1+u^2/3))\frac{\sin \mathrm{\θ}}{r^4}\mathrm{d\ζ}$

In above formula, $u=\frac{r}{2}\sqrt{\frac{\mathrm{\μ}}{\mathrm{\ρt}}},\mathrm{\Φ}\left(x\right)=\frac{2}{\sqrt{\mathrm{\π}}}{\∫}_0^x{e}^{-{\mathrm{\λ}}^2}\mathrm{d\λ}$

Wherein, ρ represents equivalent apparent resistivity; L is 1/2nd of emissive source length; λ and ζ represents integration variable; I represents electric current; R represents the distance of measuring point to emissive source mid point; T represents the time; μ ₀represent the magnetic permeability in vacuum, μ ₀=4 π 10 ^-7; θ is the angle between emissive source and measuring point.

10. a kind of electromagnetic exploration method as claimed in claim 1, is characterized in that, described calculating search coverage frequency domain equivalence apparent resistivity is calculated by following formula and obtains:

$E_x\left(\mathrm{\ω}\right)=-\frac{\mathrm{I\ρ}}{2\mathrm{\π}}\{\frac{l+x}{{r_1}^3}+\frac{l-x}{{r_2}^3}+\underset{-l}{\overset{l}{\∫}}\frac{1-(1+k_{1}r)e^{-k_{1}r}}{r^3}\mathrm{d\ζ}\}$

$d{B}_Z\left(\mathrm{\ω}\right)=2\mathrm{Iy\ρ}\underset{-l}{\overset{l}{\∫}}\frac{3-(3+3k_{1}r+{k_1}^2{r}^2)e^{-k_{1}r}}{r^5}\mathrm{d\ζ}$

In above formula,

$r=\sqrt{{(\mathrm{\ζ}-x)}^2+y^2},$

$r_1=\sqrt{{(l+x)}^2+y^2},$

$r_2=\sqrt{{(l-x)}^2+y^2},$

$k_1=\sqrt{-\mathrm{i\ω}{\mathrm{\μ}}_0/\mathrm{\ρ}},$

Wherein, ρ represents equivalent apparent resistivity; L is 1/2nd of emissive source length; ζ represents integration variable; X and y is the coordinate of measuring point; ω is angular frequency; μ ₀represent the magnetic permeability in vacuum, μ ₀=4 π 10 ^-7.

11. a kind of electromagnetic exploration method as claimed in claim 1, is characterized in that, the apparent chargeability of the time domain electric field information of described calculating search coverage, comprising:

$M_S\left(t\right)={\∫}_{-\mathrm{\Δt}}^{\mathrm{\Δt}}\frac{\mathrm{\Δ}{V}_2\left(t\right)}{\mathrm{\Δ}{V}_{1+2}\left(t\right)}\mathrm{dt}$

Wherein, M _st () is apparent chargeability to be asked; V ₂t () represents the secondary field of t, V ₁₊₂t () is t resultant field, Δ t is time window, and the span of described Δ t is: be less than four/one-period.

12. a kind of electromagnetic exploration method as claimed in claim 1, is characterized in that, the amplitude polarization coefficient of described calculating search coverage domain electromagnetic field information, adopts following formula to realize:

$P_{\mathrm{FE}}=\frac{A_L-A_H}{A_L}\·100\%$

In above formula, P _fErepresent amplitude polarization coefficient to be asked; A _lrepresent the amplitude of low frequency signal; A _hrepresent the amplitude of high-frequency signal.

13. 1 kinds of electromagnetic exploration apparatus, is characterized in that, described device comprises: information acquisition unit, calculating parameter determining unit, detection data unit, signal to noise ratio (S/N ratio) factor unit and result computing unit; Wherein,

Information acquisition unit, for obtaining search coverage information and max survey depth;

Calculating parameter determining unit, for determining to comprise emissive source length, minimum transmitting-receiving apart from the calculating parameter of, time domain transmitted waveform and frequency domain transmission waveform according to described max survey depth;

Detection data unit, for detecting described search coverage according to the described calculating parameter determined, obtains detection information data;

Signal to noise ratio (S/N ratio) factor unit, for calculating the time domain signal to noise ratio (S/N ratio) factor of described detection information data, judges the validity of described detection information data according to the described time domain signal to noise ratio (S/N ratio) factor;

Result computing unit, for being effective detection information data according to described judged result, calculates the amplitude polarization coefficient of search coverage time domain and the equivalent apparent resistivity of frequency domain, the apparent chargeability of time domain electric field information and domain electromagnetic field information.