Transient Electromagnetic Survey Equipment Tem Tdem Land Survey Product Time Domain Resistivity Sounding Method Electric And Magnetic Survey System
The electrical source transient electromagnetic (TEM) method has the advantages of large detection depth, low terrain constraints and high efficiency.
Application
Mineral Surveys
Geothermal Resources Exploration
Tectonic Exploration
Hydrological and Engineering Geological Surveys
Environmental Investigation and Monitoring
Municipal engineering and pollution surveys
Geological survey of coal strata
Good conductor metal ore detection
Time shift detection of oil and gas resources
Magnetic dipole field source
The whole system consists of two parts: transmitting and receiving, and the working process is divided into three parts: transmitting, electromagnetic induction and receiving. When a step current is passed through the transmitting line, the transmitting current suddenly drops from a constant value to zero, and the sudden change of current in the transmitting line will certainly make the primary magnetic field around the transmitting line change instantly and drastically. When the vortex field encounters a good conductive geological body in the ground, it will generate an induced current in its internal excitation, and the induced current will generate a new induced magnetic field, that is, the secondary magnetic field, due to the heat loss of the induced current in the good conductive geological body, the secondary magnetic field decays roughly with time according to the exponential law, and the secondary magnetic field received by the receiving coil contains the geophysical correlation of the conductive geological body in the ground in the relationship with time. The geophysical information about the subsurface conductive geology is contained in the time dependence of the secondary magnetic field received by the receiving coil.
The early time domain electric and magnetic fields are proportional to the earth resistivity, which is the same as the variation of the far zone electromagnetic field in the frequency domain; the late time domain electromagnetic field is proportional to the 3/2 power of the conductivity, which is the same as the variation of the real component of the secondary magnetic field in the near zone electromagnetic field in the frequency domain. The late time domain electromagnetic field is very sensitive to changes in the earth's conductivity, and since the time domain electromagnetic method can measure the secondary field, which is very sensitive to the earth's conductivity, after disconnecting the primary field, it is better than the frequency domain electromagnetic method for detecting good conductors.
| Transmitting voltage: ≤200V |
| Transmitting current: ≤50A |
| Current measurement precision: current range before power supply being cut off |
| is 0~50A, display resolution is 0.01A. |
| Power supply frequencies: 0.0625Hz, 0.125Hz, 0.25Hz, 0.5Hz, 1Hz, 2Hz, 4Hz, |
| 8Hz, 16Hz, 32Hz |
| Transmitting waveform: +ON, OFF, -ON, OFF, equal width and dual polarity |
| Turn-off delay time: 1μs~1000μs |
| Turn-off time: ≤1.2μs (pure resistance), changing with the transmitting current |
| and transmitting coil when connecting to the coils |
| Damping resistance: 1000Ω |
| Transmitting coil: 0.1km×0.1km single turn ~ 2km×2km single turn |
| Synchronization mode: external synchronization (cable, GPS) |
| Power supply: internal 12V8.6Ah rechargeable battery (or external 12V power |
| supply) lasting for over 10 hours |
| Dimension: 525×436×217mm3 |
| Weight: 18.5kg |
| Working temperature: -10°C~+50°C |
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