What Is Geophysical Exploration Technology?

The so-called physical exploration, or geophysical exploration, is to measure the physical quantities of the strata (such as velocity, density, resistivity, etc.), and analyze and study them in combination with known geological data to achieve the purpose of inferring geological conditions.

In contrast, the measurement through the chemical characteristics of the strata is called geochemical exploration. For example, just like in a hospital, the laboratory department does X-rays, B-ultrasound, and nuclear magnetic resonance, which are geophysical methods, while blood tests and pathological analysis are geochemical methods.

Physical test methods determine the location of the lesion, but cannot confirm the physiological tissue characteristics of the lesion, while blood tests and pathological test analysis can give the precise values of all indicators and tissue characteristics. When a patient goes to the hospital for treatment, the doctor usually chooses the "geophysical exploration" method after the initial consultation, and then does "geochemical exploration", because geophysical exploration is simple, fast, harmless to the patient, and will not interfere with the diseased tissue. After the location of the lesion is accurately determined, pathological test analysis is performed for precise quantitative detection.

What are the applications of geophysical technology?

Geophysical technology has been developed for nearly a hundred years. It is widely used and mature in the field of mineral resource exploration and geological exploration. The main methods are: electrical method, magnetic method, gravity, seismic and radioactive methods. We apply geophysical technology to the field of environmental engineering. The technical means can be used for reference, but the understanding of the measurement target is safe and different. In terms of measurement dimension, resolution, formation continuity, etc., they are completely different. Therefore, it cannot be simply copied, and a lot of applicability research and development is needed.

What are the commonly used geophysical methods in soil and groundwater pollution investigation?

For soil and groundwater surveys, we often use three tools: resistivity method (ERT, resistivity tomography, similar to CT), ground penetrating radar (GPR, similar to B-ultrasound) and induction electromagnetic (EM, similar to oximeter and sphygmomanometer)

The three methods also have their own advantages and applicability. We will try to choose at least 2 methods according to the actual situation of the site, so as to take the advantages of each method and verify the results of different methods to ensure the accuracy of the test results.

This is the layout of the test line of the resistivity method. A row of electrodes is laid on the test section, and the electrodes are inserted into the soil for 20-30cm.

The advantage of the resistivity method is the measurement of vertical sections, and the depth can reach 100 meters or even deeper.