Transient electromagnetic, the principle of transient electromagnetism

The best is the best!

In China, the mainstream incoming products are the ProTEM from Geonics of Canada and the Terra TEM transient electromagnetic instrument from Geoinstruments of Australia. The advantages of PROTEM are outstanding: high accuracy, short turn-off time, stable performance, and occupies the main market in the world and China; The disadvantage is that it is not as easy to move as the Terra Tem (due to the separation of the transmitting wireframe from the receiving wireframe), and the design is not as novel as the Terra Tem.

Terra TEM is just the opposite: it is not as good as ProTEM in terms of performance, but because the transmission and reception are integrated into one, it is more convenient to move (but the mutual interference of the two frames has also been bothering the existing users of Terra TEM), and the appearance is more beautiful (in my opinion). **Aspects are naturally higher than Terra specific information you can contact Helvara Union (China**, technical support center, after-sales service center), Terra TEM specific information contact Laurey (China**, technical support center, after-sales service center).

As for the EH4 you mentioned, as said on the first floor, it is not a transient electromagnetometer, but an magnetotelluric instrument. Its advantage is that it is not high, and it can also be used as a controllable source; The disadvantage is that the frequency band ratio is narrow, and the controllable source can only be shallow. Similar products include Canada's V8, the United States' GDP-32 and Germany's equipped with the world's most advanced magnetic sensors, which once led the field of magnetotellurics.

However, the functional integration is not as fast as V8 and GDP-32. V8 and GDP-32 can be regarded as base stations, which can not only do MT, AMT, CSAMT but also IP, and also have the function of transient electromagnetic meters (the performance of course cannot be compared with ProTem and Terra Tem, just like people who like photography prefer to buy a professional camera rather than buy a mobile phone with a camera function for photography). The controllable source of ADU-07 has finally passed the cumbersome software and hardware tests, and it is said that their transmission system is a unique three-pole emission system, which can measure tensor and accurately measure the occurrence and strike of the ore body, and our brother units are looking forward to it.

Big brother, EH4 is for magnetotellurics, not transients! Protem is transient.

The YCS150 mine transient electromagnetic method is based on the difference between the conductivity and magnetic permeability of the rock (ore) in the earth's crust as the main material basis, according to the principle of electromagnetic induction, the use of non-grounded loop or grounding wire source to send a pulse magnetic field to the underground, during the gap of the primary pulse magnetic field, the use of coil or grounding electrode to observe the secondary eddy current field, and study the spatial and temporal distribution of the field, to find underground mineral resources or solve other geological problems.

Application field of intrinsically safe transient electromagnetic instrument for mining.

detection of aquifers, fault aquifers, stratigraphic structures and collapse columns at the ground; Underground detection of water bearing and medium coal structures in and around the mining area and in front of the excavation head; Detection of the buried depth and occurrence of the benign conductive ore body, and the detection of the ore structure; Detection of old kilns and their water content; Engineering Exploration and Environmental Exploration.

Characteristics of intrinsically safe transient electromagnetic instrument for mining.

Transmitter, receiver and power supply are integrated; High work efficiency, hundreds of bathymetry points can be completed every day; The mine is about 150 meters ahead of the detection; The short turn-off time greatly reduces the measurement blind area; Wireless export of measurement data; High signal-to-noise ratio; Strong ability to penetrate low resistance; High-density, high-resolution, high-dynamic range fast sampling; Intelligent prompt, automatic drawing after measurement.

Intrinsically safe transient electromagnetic instrument index for mining.

CPU: low-power ARM11

Operating system: Screen: 5 inch LCD screen 800*400 display mode, touch screen operation.

Power supply: Data export: wireless transmission.

Instrument power supply: built-in high-energy battery, capacity 12V 5Ah Adapt to the environment: moisture-proof, dust-proof, explosion-proof.

Operating temperature: -10 50

Receiver specifications.

High-speed AD converter: 24bit;

Dynamic Range: 175db;

System resolution: 29 bits.

Signal resolution: 24 bits.

Sample rate: Number of overlays: 64 10240

Small resolution: 10nv

Synchronization mode: internal synchronization of the instrument.

Operating temperature: -20 60

Transmitter specifications.

High Output Power(W):18;

Transmit Output Voltage:;

Transmitter coil size: 2-2 coils;

Transmitting frequency:,25Hz,;

Transmit Current:;

Waveform: A bipolar square wave with a duty cycle of 1:1.

Transient electromagnetic method, also known as time domain electromagnetic methods, referred to as TEM, is a method of using a non-grounded loop or grounding wire source to transmit a pulsed magnetic field to the ground, and using a coil or grounding electrode to observe the secondary eddy current field during the interval of a pulsed magnetic field. To put it simply, the basic principle of transient electromagnetic method is the law of electromagnetic induction. The decay process is generally divided into early, middle, and late stages.

The early electromagnetic field is equivalent to the high-frequency component in the frequency domain, with fast attenuation and small skin depth. The late component is equivalent to the low-frequency component in the frequency domain, with slow attenuation and large skin depth. By measuring the variation of the secondary field with time in each time period after power failure, the characteristics of geoelectric power at different depths can be obtained.

Transient electromagnetics are tools used to detect surface aquifers. Geonics Canada is a professional company specializing in the development and production of time-domain electromagnetic instruments, with a total of nearly 20 kinds of time-domain electromagnetic measuring instruments, which are used in a variety of different purposes and occasions, and enjoy a high reputation in the world. Since 1978, the company has developed and produced transient electromagnetic instruments, has been updated many times, and the PROTEM47, PROTEM47HP (underground water exploration system), PROTEM57-MK2 and PROTEM67 transient electromagnetic instruments currently on the market occupy a large market share of this type of instrument detector in the world.

Detection of aquifers, faults, coal seam structures and subsidence on the ground.

Downhole probe the water storage structures inside and outside the mining area and in front of the excavation head.

Detect the buried depth and occurrence of the good conductive ore body before completion, and detect the ore structure.

Explore and measure the old kiln and its water content.

Engineering Exploration and Environmental Exploration.

oil and gas field exploration, etc.

TEM47, with a maximum exploration depth of 150m, collectively referred to as PROTEM47 TEM57-MK2, and a maximum exploration depth of 500m, collectively referred to as PERTEM57 TEM-67, with a maximum exploration depth of 1000m-1200m, collectively referred to as PROTEM67

Strengthened TEM 67HP, maximum exploration depth 1500m TEM47HP, downhole water exploration, detection distance 100m-150m BH43-3 3D transient electromagnetic instrument in drilling, can work in 2,000m deep borehole, detection radius 150-250m and so on.

Simultaneous observation of three parts,.

Short turn-off time and large amount of information: Turn-off time is one of the important technical indicators of transient electromagnetic, long turn-off time will lose shallow signal, weaken the intensity of the secondary teasing stove, and directly affect the detection effect. The PROTEM47 shutdown time can be as short as the shutdown time depends on transmitter performance, transmit current, and transmitter coil size.

High resolution and large dynamic range: due to transients, the electromagnetic field varies from n 105 V to late. Up to 6 orders of magnitude, so high signal resolution and dynamic range are required.

ProTem has a signal resolution of 24 bits, a system resolution of 29 bits, and a dynamic range of up to 175dB.

High signal-to-noise ratio: Protem transient solenoids take a variety of measures to improve signal-to-noise ratios, including suppressing power-frequency interference, using "smart superposition" techniques and increasing repetition rates, among others. Repetition rate refers to the number of bipolar pulses that can be emitted in 1 second.

The repetition rate of protem is, i.e., optional. As a result, it can emit 14,250-2,400 pulses and receive the same number of transient electromagnetic signals in a 30-second observation time. If the repetition rate is 25 Hz, i.e. 40 ms to 24,000 ms, it can only transmit and receive 1,500 signals in a 30-second observation time, i.e., the signal-to-noise ratio of the former is 10 times higher than that of the latter in the same observation time.

Flexible Observation Devices: The Transient Electromagnetic Method has five field observation devices, which are suitable for different exploration targets and depths. The five devices are:

Overlapping loops, central loops, dipoles Outside the large fixed loop, observation Observation Inside the large fixed loop. The first three units are suitable for shallow exploration, and the latter two are suitable for deep exploration. Due to the transmit and receive separation of the PROTEM transient electromagnetic instrument, it is suitable for all four devices except the overlapping loop device.

However, if the integrated transmitting and receiving device is adopted, it is only suitable for the overlapping loop device, and when the other four observation devices are used, the weak transient field signal in the receiving coil must be transmitted to the receiver with a long signal cable, so as to bring in the interference that cannot be improved.

High stability and wide operating temperature: Stability includes the repeatability of observations and the failure rate of the instrument. ProTem has 100% repeatability of observations and extremely low instrument failures.

With an operating temperature range of -40 +60, Protem can be observed smoothly in any season and in any area; If the operating temperature range is narrow, field observations can only be made in the right season or in the right area.

Transient electromagnetic method is a method to detect the resistivity of the medium by using a non-grounded loop or a grounding wire source to transmit a pulsed magnetic field to the ground, and using a coil or grounding electrode to observe the secondary induced eddy current field caused in the underground medium during the intermittent period of the primary pulsed magnetic field. Its basic working method is to set up a transmission coil with a certain waveform current on the ground or in the air, so as to generate an electromagnetic field in the space around it, and generate an induced current in the underground conductive rock ore body

After a power failure, the induced current decays over time due to heat loss.