Transient Electromagnetic TEM Equipment Time Domain Electromagnetic TDEM Geophysical Magnetic Survey Instrument
Transient electromagnetic method (TEM) is also called Time domain electromagnetic Method (TEM). It transmits a electromagnetic pulse into the ground by using an ungrounded loop or ground wire source. During the interval of the magnetic pulse, a coil or ground electrode is used to observe the secondary eddy current field.
Simply put, the fundamental principle of TEM 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 components in the frequency domain, which attenuates quickly and has a small skin depth. While the late component is equivalent to the low frequency component in the frequency domain, slow attenuation, large skin depth. The geoelectric characteristics of different depths can be obtained by measuring the change law of secondary field with time in each time period after power failure.
Application:
- Surface detection of aquifers, fault water bearing, coal seam structure and subsidence
- The water storage structure inside and outside the mining area and in front of the header is detected downhole
- To detect the depth and occurrence of good conductive ore body, and to detect the structure of ore accumulation
- Detect the old kiln and its water content
- Engineering exploration and environmental exploration
- Oil and gas exploration and so on
WTEM-2 Medium-Deep/Deep TEM Exploration System (hereafter also refer to as WTEM-2 system or system) applying to medium-deep/deep transient electromagnetic exploration, is one of our latest researches with all functions of transient electromagnetic survey system. It boasts high power, short turn-off time, high reliability, strong anti-interference performance (against atmospherics, 50Hz or 60Hz industrial frequency interference), lightweight and low power consumption.
Standard configuration of Transient Electromagnetic TEM Equipment Time Domain Electromagnetic TDEM Geophysical Magnetic Survey Instrument
- WTEM-2J TEM Exploration System Receiver
- WTEM-1D 10kw High-Power Transmitter
- WTEM-2T/GPS Transmitter Synchronized Controller
- Pocket PC (PDA) to control the TEM system receiver and the system.
Optional instruments:
- PTT-40A Antenna & Adapter
WTEM-2J receiver has to work together with a WTEM-1D transmitter to finish medium-deep or deep sounding; in the mode of GPS synchronization, a WTEM-2T/GPS synchronized controller is needed to synchronize WTEM-2J receiver and the transmitter.
PTT-40A Receiver Antenna & Adapter is a specific antenna (or receiving coil) designed for TEM system receiver, which consists of an detached antenna and adapter, with large equivalent area and high signal-to-voice ratio, easy for field layout and free from limitation of landform.
Loop applicable may be central loop or coincident loop, one TEM system transmitter working together with one TEM system receiver; or be large loop, one TEM system transmitter in association with several TEM system receivers. According to different geological situations, user could choose an appropriate system to finish surveying tasks of quick general survey, 3D graph coloring up, deep mine finding.
It is mainly used for surveying metal mine, coal-mine, oil and gas field, geothermal field, and applies in hydrology and engineering geological prospecting as well.
Technical Specifications of Transient Electromagnetic TEM Equipment Time Domain Electromagnetic TDEM Geophysical Magnetic Survey Instrument
| Transmitter |
| 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 |
525×436×217mm 3 |
| Weight |
18.5kg |
| Working temperature |
-10°C~+50°C |
| |
Receiver |
| Number of channel |
1 |
| Pre-amplification gain |
8, 32 times |
| Main amplification gain |
1, 2, 4, 8, 32, 64, 128 times |
| Band-pass |
0~50k Hz (liner phased filter), full band-pass 0~400k Hz |
| Suppression |
80dB |
| A/D |
16 bit |
| Min sample interval |
1μs |
| Trace number |
≤128 |
| Stacking times |
1~9999 time |
| Synchronization mode |
internal 12V9.6Ah rechargeable battery (or external 12V power supply) lasting for over 10 hours |
| Pocket PC |
Windows Mobile 6.0 system with software such as Word, Excel, etc., 320x240 true color, 64MB Flash Rom/ 64MB SDRAM/64MB 2GB CF card, able to store over 200,000 readings of sampled data,2 original rechargeable batteries |
| Ports |
Bluetooth, infrared and serial port |
| Dimension |
340×295×152mm |
| Weight |
5.3kg |
| Working temperature |
-10°C~+50°C |
Main Functions and Features of TDEM Time Domain TEM Transient Electromagnetic Equipment Geophysical Exploration Instrument for Groundwater and Mining
- All-round optimization of WTEM-2J receiver: Except for the power switch, all operations are carried out in pocket PC through Bluetooth.
- Improved WTEM-2T/GPS transmitter synchronized controller: a better GPS module and antenna with higher sensibility, faster in synchronization speed, compacter in size and lighter in weight.
- Support several synchronization mode:
-
- cable synchronization
- GPS synchronization
- "GPS + Clock" synchronization (optional)
When GPS satellite signal is very weak or disappears, the quartz crystal will perform synchronization with error less than 1μs/hour.
The latter two synchronization modes require a WTEM-2T/GPS synchronized controller. Once start up, it only takes no more than 2 minutes to get the transmitter and the transmitter synchronized if satellite signal is good.
Features:
One instrument with multiple functions: this system is integrated with functions of a transmitter and a receiver, portable and simple in connection. WTEM-3Q has function of deep exploration with an external high-power TEM transmitterin cable synchronization or mode GPS synchronization mode.
High reliability, low power consumption: refined receiver and circuitry, reasonable heat dissipating system design, sealed and rugged mechanical structure, ensuring high reliability, low power consumption and convenient operation.
Remote control: Tablet PC based Bluetooth wireless communication technology enables it to control the receiver in 10 meters, such as setting parameters, starting measuring, transferring and displaying the measured results.
High anti-interference performance: program controls the filter to give accurate power supply frequency; besides, data stacking and software filtration also do good to this performance.
Flexible power supply mode: the power supply waveform with standard duty cycle (1:1) and the power supply waveform with user-defined power supply pulse width, optional, so that the instrument has a wider exploration application. width
Adjustable number of time windows: operator could set number of time windows, linear or logarithmic; crystal oscillator accomplishes timing, with stable and precise time-to-depth ratio. Sampling window arrangement is reasonable, imaging the true subsurface structure. It provides references to complex geological problems.
Multiple working mode: single-point and continuous working mode,optional.
Wide depth range prospecting: this system is equipped with high-power transmitter which could easily inspect the objects deep in meters to hundreds of meters (for shallow exploration)
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