Common Digital in Geophysical Electrical Method
Supply Current: 1mA ~ 2A. When the supply current of less than 10mA, low SNR. Improving ground conditions improve power supply current is the most effective measures to ensure data quality.
Observation of the potential difference: from less than a few millivolts to volts. If the signal is less than 0.1mV, the signal is not reliable, however, offshore continuous high-density electrical exception. The voltage value observed positive and negative, positive and negative values are normal.
Subsurface resistivity: Depending on lithology, humidity, porosity, temperature and the type and nature of the pore fluid.
Here are some common medium resistivity (Ohm-m):
• Seawater 0.1 --1
• Clay 1--100
• Freshwater 10--100
• Alluvium 1-- 1,000
• Sandstone 1-- 1,000
• Limestone 10 - 10,000
• Gravel 100-- 10,000.