CN102162860A - High-power extremely low frequency and ultralow frequency artificial source electromagnetic method for geological prospecting - Google Patents
High-power extremely low frequency and ultralow frequency artificial source electromagnetic method for geological prospecting Download PDFInfo
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- CN102162860A CN102162860A CN201010598021XA CN201010598021A CN102162860A CN 102162860 A CN102162860 A CN 102162860A CN 201010598021X A CN201010598021X A CN 201010598021XA CN 201010598021 A CN201010598021 A CN 201010598021A CN 102162860 A CN102162860 A CN 102162860A
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Abstract
The invention discloses a high-power extremely low frequency and ultralow frequency artificial source electromagnetic method for geological prospecting. In the method, a transmitting antenna is arranged in a region with extremely low electric conductivity; the qualified apparent resistivity of the region is in the range of 5,000 to 20,000 ohm m and the thickness of a high resistance layer of the region is in the range of 20 to 30km; the transmitting antenna is an extremely low frequency or ultralow frequency transmitting antenna, is erected in a low frame mode and has the length of not less than 60km; the transmitting antenna adopts a power grounding standard; grounding resistance is permanent; the resistance value of the grounding resistance is not more than 2 ohms; and a feeding transmitter has the power of not lower than 500kw, the frequency stability superior to 1*10<-8> and the current of 300 to 350A. For the artificial source electromagnetic method, a transmitted signal has high strength, the amplitude-phase is stable, the signal-to-noise ratio, anti-jamming capability, measurement accuracy and efficiency are high, the detection range is wide, measurement is simple and convenient, and conditions are provided for earthquake prediction, three-dimensional electromagnetic prospecting and development of an ocean resource detection technology.
Description
Affiliated technical field
The present invention is a kind of high-power artificial source's electromagnetic method that is used for geologic prospecting of utilizing extremely low frequency or ultralow frequency radio transmission technology to combine with geophysics and produce, belongs to a kind of AC electrical method in the resistivity prospecting.
Background technology
Geologic prospecting has several different methods in the geophysics subject, for example sound method exploration (artificial earthquake method), magnetometer survey, gravity prospecting, resistivity prospecting etc., and wherein, resistivity prospecting has advantages such as efficient height, cost is low, applicability is wide, is generally used both at home and abroad.The electrical method of Ti Chuing is in early 1950s the earliest, and the magnetotelluric sounding method by A.H.Tikhonov proposes respectively in nineteen fifty-three in nineteen fifty and L.Cagniard is called for short the MT method.The MT method be utilize ppt that nature produces on earth by thunder and lightning and solar particle radiation etc. to the very low electromagnetic wave of thousands of hertz frequencies as the natural electromagnetic radiation source, can produce reflection electromagnetic wave when inciding the ground penetrating Different Strata by this electromagnetic wave, the electromagnetic wave that utilizes detection instrument to receive incident and reflection again can be analyzed the impedance of Different Strata, difference according to ground conductivity, can survey each layer electrical resistance more than underground hundred kilometers, thereby be finally inversed by stratal configuration, comprise subterranean resource, as metallic ore, oil, rock gas, underground water etc.The MT method is wide with its investigative range, investigation depth is big, and low cost and other advantages has obtained in fields such as resource exploration and geology detectings using widely.But, MT method essence is a kind of natural source method, natural source signal complexity, extremely unstable, signal weak, be subject to disturb, development along with resource exploration work, various electric equipments increase sharply, and the electromagnetic interference (EMI) showed increased is a little less than the antijamming capability of MT method, the problem that detection accuracy is low is more outstanding, makes to use to have run into very big difficulty.
Artificial source's electromagnetic method appearred in mid-term the 1950's, for example, CSAMT method and TEM method etc., utilize the high s/n ratio signal of artificial emission to replace natural field signal, the artificial electromagnetic ripple that produces from a few tenths of to thousands of hertz by transmitter, small-sized transmitter commonly used is tens kilowatts, maximum transmitter can arrive one, 200 kilowatts, the two-terminal-grounding cable that utilizes 2～4km is as the radiating antenna radiated electromagnetic wave, general tens to tens amperes of antenna current, lay for moving, usually near measurement point, lay, about 10 kilometers of effective detection ranges, high-power transmitter can reach the twenty or thirty kilometer, about investigation depth 1km, this method is the signal noise ratio height in effective investigative range, signal stabilization, and antijamming capability is strong, the detection accuracy height has overcome the deficiency that the MT method exists.Artificial controlled audio-frequency magnetotelluric magnetic method (being called for short the CSAMT method) and artificial moving source TDEM (being called for short the TEM method) are two kinds of artificial source's electromagnetic methods commonly used at present, but, these methods belong to artificial moving source frequency domain electromagnetic methods of miniwatt and TDEM, several kilowatts transmitter and gen-set heaviness, the ground connection difficulty, be unsuitable for ungetable mountain area and use, and signal cover is little, only has tens kilometers usually.Wherein, the CSAMT method is limited by the near field, and its frequency of operation only only limits to audiorange, and investigation depth is shallow, and investigative range is little; Though the TEM method is not limited by or not the near field, utilize transition vagabond current decay very fast, problem such as detection range is very short also can't satisfy the needs than deep layer resource and large tracts of land exploration.Utilize the emissive power method that improves transmitter effectively to address the above problem, still, along with the increase of transmitter power, its weight and volume is heavy more, the transportation difficulty, so that many places can't be used.The Russian scientist proposition eighties in last century has also been built the former logos of Magnetohydrodynamic(MHD) generator (being called for short the MHD method), and its signal cover can reach more than 100 kilometer, but instrument is too heavy, and use cost is high, is difficult to promote.
The radio magnetic method that on CSAMT method basis, grows up, its principle be under specific geologic condition by setting up a fixing emissive source, carry out high-power ultralow frequency method for transmitting.Russia once reported a kind of specific ultra-low frequency emissive source technology, specifically be at parallel 110kv line of electric force at a distance of two 60km two-terminal-groundings of 10km, maximum current is 330A, its directivity is that antenna direction is 8 fonts, this wireless electrical measuring method mainly is fit to ultralow frequency work, because the directivity restriction, electric wave can not omnidirectional cover, thus the precision that influence is measured.
Summary of the invention
Deficiency at above-mentioned prior art exists the invention provides a kind of high-power extremely low frequency and ultralow frequency artificial source electromagnetic method that is used for geologic prospecting, mainly may further comprise the steps:
Select the extremely low area of conductance that emitting antenna is installed, the qualified apparent resistivity of this area is 5000～20000 Ω m, resistive formation thickness 20～30km;
Wherein, emitting antenna is extremely low frequency or ultralow frequency emitting antenna, adopts low frame form to set up, and the length of emitting antenna is not less than 60 kilometers;
Wherein, emitting antenna adopts standard power ground, and stake resistance is a permanent type, and its resistance value is not more than 2 Ω, and the transmitter power of feed is not less than 500kw, and frequency stability is better than 1 * 10
-8, electric current 300～350A.
Described emitting antenna adopts 60～110kv line of electric force of two-terminal-grounding, is connected with transmitter by feeder line.
Vertical two width of cloth emitting antennas of laying of described emitting antenna are cruciform or L type, are powered respectively by two transmitters, work alone.
The vertical emitting antenna of laying of described two width of cloth is EW antenna and NS antenna, adjusts the phase place of two width of cloth antennas and can control radiation direction, can both obtain maximum field strength in any direction and cover.
Described EW antenna and NS antenna are by the public middle earth point of transmitter.Described EW antenna and NS antenna are by the public middle earth point of transmitter.
Adopt mobile electromagnetic measurement equipment to compare with existing, 0.1～300Hz the extremely low frequency or the ultralow frequency electromagnetic signal of artificial source's electromagnetic method emission that the present invention proposes, its signal intensity is big, amplitude, phase place are very stable, the signal to noise ratio (S/N ratio) height, can eliminate interference effectively, it is strong to have an antijamming capability, the advantage that measuring accuracy is high.When minimum transmission frequency was 0.1～0.5Hz, investigation depth can reach tens of kilometers; The signal to noise ratio (S/N ratio) that transmits is 10～20db, and its effective covering radius reaches 1000～3000km; Only need lay measuring receiver at measurement point, save the transportation of transmitter, it is big to have investigative range, measure easy, efficient height, advantage such as operating cost is low; In addition, the electromagnetic signal of emission covers wide, signal stabilization, and consistance is strong on spatial domain and time domain, correlativity good, is fit to the large tracts of land networking and receives, and be earthquake prediction, 3 D electromagnetic exploration, and the development of ocean resources Detection Techniques provides condition.
Description of drawings
Fig. 1 is artificial source's electromagnetic method antenna emission principle figure.
Fig. 2 is used for the high-power extremely low frequency of geologic prospecting and the emitting antenna schematic layout pattern of ultralow frequency artificial source electromagnetic method for the present invention.
Below in conjunction with accompanying drawing high-power extremely low frequency and the ultralow frequency artificial source electromagnetic method that is used for geologic prospecting of the present invention is further described.
Embodiment
As shown in Figure 2, select the extremely low area of conductance, for example Archean era the rock area, qualified apparent resistivity is at 5000-20000 Ω m, resistive formation thickness 20-30km, and its area can hold the layout of emitting antenna, lay extremely low frequency and ultralow frequency emitting antenna in this area, antenna adopts low frame form, can be 60～110kv line of electric force of the vertical two-terminal-grounding of single pair or two pairs, and the latter will keep 360 degree omni-directional; Every slave antenna length is not less than 60 kilometers, and stake resistance is a permanent type, presses standard design power ground, and stake resistance is not more than 2 ohm, and the transmitter power of every slave antenna feed is not less than 500kw, and frequency stability is better than 1 * 10
-8, antenna maximum current 350A sets up a kind of large-scale fixing broadcast-type radio-transmitting station in the above conditions, and its frequency is 0.1～300Hz, and the radiation magnetic moment of transmitter can reach 0.2～1 * 10
6Akm
2Its ultimate principle is:
With exchange current, electric current is through underground formation loop, and is high as the ground conductance in the feedback of two-terminal-grounding lead, and the ground of flowing through very soon forms short circuit, and is extremely low as conductance, and vagabond current can go deep into the stratum and form electric current loop, as shown in Figure 1,
In the feedback of two-terminal-grounding lead at formula be along antenna direction electric field and magnetic field with the electromagnetic field component that exchange current produces
η
fIt is the ground surface impedance of measurement point.
λ is a wavelength, and r is a distance, all is under the fixed value situation, magnetic moment I
mDl directly is directly proportional with electric field and magnetic field
I
mDl=i ω μ
0IdS, I are the electric current in the electric current loop, and dS is the area of electric current loop,
The skin depth on stratum
The magnetic moment Imd1 of the electromagnetic field of radiation and antenna is directly proportional, and promptly is directly proportional with antenna current I, antenna length L and skin depth δ, by setting above-mentioned parameter, has determined radiation field intensity.
According to above principle, the electromagnetic method that the present invention proposes, when the length of emitting antenna is 100km, electric current 300A, during frequency 1Hz, skin depth 30km, the I dS of its magnetic moment can reach 6.4 * 10
5Akm
2And the CSAMT antenna length is as being 2km, during electric current 20A, and skin depth 1.5km, the I dS of its magnetic moment has only 6 * 10Akm
2, the two differs 10
4, promptly the radiation field intensity of electromagnetic method of the present invention is big to up to ten thousand times than CSAMT.
Utilize extremely low frequency 0.1～30Hz, or ultralow frequency 30～300Hz frequency range, used emission field source condition is not subjected to prescribed limits, typically be arranged as the layout type of orthogonal EW antenna and NS antenna, guaranteed the omnidirectional radiation of emitting antenna, by adjusting the phase place between EW antenna and the NS antenna, make the equal of any direction measuring point can reach maximum, as shown in Figure 2, thereby guaranteed the precision of measuring, evidence, electromagnetic method of the present invention all can produce extremely low frequency or ultralow frequency radiowave, and are used for geophysical survey.
Claims (5)
1. high-power extremely low frequency and ultralow frequency artificial source electromagnetic method that is used for geologic prospecting mainly may further comprise the steps:
Select the extremely low area of conductance that emitting antenna is installed, the qualified apparent resistivity of this area is 5000～20000 Ω m, resistive formation thickness 20～30km;
Wherein, emitting antenna is extremely low frequency or ultralow frequency emitting antenna, adopts low frame form to set up, and the length of emitting antenna is not less than 60 kilometers;
Wherein, emitting antenna adopts standard power ground, and stake resistance is a permanent type, and its resistance value is not more than 2 Ω, and the transmitter power of feed is not less than 500kw, and frequency stability is better than 1 * 10
-8, electric current 300～350A.
2. according to the high-power extremely low frequency that are used for geologic prospecting and the ultralow frequency artificial source electromagnetic method of claim 1, it is characterized in that emitting antenna adopts 60～110kv line of electric force of two-terminal-grounding, is connected with transmitter by feeder line.
3. according to the high-power extremely low frequency that are used for geologic prospecting and the ultralow frequency artificial source electromagnetic method of claim 1, it is characterized in that vertical two width of cloth emitting antennas of laying of emitting antenna, be cruciform or L type, power respectively, work alone by two transmitters.
4. according to the high-power extremely low frequency that are used for geologic prospecting and the ultralow frequency artificial source electromagnetic method of claim 3, it is characterized in that the vertical emitting antenna of laying of two width of cloth is EW antenna and NS antenna, adjust the phase place of two width of cloth antennas and can control radiation direction, can both obtain maximum field strength in any direction and cover.
5. according to the high-power extremely low frequency that are used for geologic prospecting and the ultralow frequency artificial source electromagnetic method of claim 4, it is characterized in that EW antenna and NS antenna are by the public middle earth point of transmitter.
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103091718A (en) * | 2011-11-04 | 2013-05-08 | 中国船舶重工集团公司第七研究院 | Method of using extremely low frequency marine electromagnetic method to conduct marine oil and gas resources exploration |
| CN105807325A (en) * | 2014-12-31 | 2016-07-27 | 中国船舶重工集团公司第七研究院 | Frequency domain aviation extremely low frequency electromagnetic method |
| CN108241175A (en) * | 2016-12-23 | 2018-07-03 | 中国船舶重工集团公司第七研究院 | A kind of time-domain electromagnetic exploration method using high-power stationary source |
| CN112285785A (en) * | 2020-03-09 | 2021-01-29 | 中国科学院地质与地球物理研究所 | Electromagnetic detection method without near-field effect |
| CN112946765A (en) * | 2020-12-29 | 2021-06-11 | 中国船舶重工集团公司第七研究院 | Impedance tensor calculation method of WEM method |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101625413A (en) * | 2009-08-07 | 2010-01-13 | 北京大学 | Oil-gas exploration method |
-
2010
- 2010-12-21 CN CN201010598021XA patent/CN102162860A/en active Pending
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101625413A (en) * | 2009-08-07 | 2010-01-13 | 北京大学 | Oil-gas exploration method |
Non-Patent Citations (4)
| Title |
|---|
| 《中国地球物理2010-中国地球物理学会第二十六届年会、中国地震学会第十三次学术大会论文集》 20101017 陆建勋 "极低频探地工程"简介 全文 1-5 , * |
| 《舰船科学技术》 20100630 卓贤军等 "极低频探地工程"在资源探测和地震预测中的应用与展望 第3-7、30页 1-5 第32卷, 第6期 * |
| 卓贤军等: ""极低频探地工程"在资源探测和地震预测中的应用与展望", 《舰船科学技术》, vol. 32, no. 6, 30 June 2010 (2010-06-30) * |
| 陆建勋: ""极低频探地工程"简介", 《中国地球物理2010-中国地球物理学会第二十六届年会、中国地震学会第十三次学术大会论文集》, 17 October 2010 (2010-10-17) * |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103091718A (en) * | 2011-11-04 | 2013-05-08 | 中国船舶重工集团公司第七研究院 | Method of using extremely low frequency marine electromagnetic method to conduct marine oil and gas resources exploration |
| CN105807325A (en) * | 2014-12-31 | 2016-07-27 | 中国船舶重工集团公司第七研究院 | Frequency domain aviation extremely low frequency electromagnetic method |
| CN105807325B (en) * | 2014-12-31 | 2018-07-13 | 中国船舶重工集团公司第七研究院 | A kind of frequency domain aviation Extremely Low Frequency Electromagnetic method |
| CN108241175A (en) * | 2016-12-23 | 2018-07-03 | 中国船舶重工集团公司第七研究院 | A kind of time-domain electromagnetic exploration method using high-power stationary source |
| CN112285785A (en) * | 2020-03-09 | 2021-01-29 | 中国科学院地质与地球物理研究所 | Electromagnetic detection method without near-field effect |
| CN112946765A (en) * | 2020-12-29 | 2021-06-11 | 中国船舶重工集团公司第七研究院 | Impedance tensor calculation method of WEM method |
| CN112946765B (en) * | 2020-12-29 | 2023-02-17 | 中国船舶重工集团公司第七研究院 | Impedance tensor calculation method of WEM method |
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Application publication date: 20110824 |