Methods
Geophysical investigations using non invasive techniques to delineate geological structures or constructions such as excavations, tunnels, utilities, are based on physical contrasts of properties between target objects and the surrounding medium. This property, in the most cases mass density, magnetic susceptibility, electrical resistivity, elastic wave velocity, radioactivity or other key parameters, which different methods are based on. Relationship between lithological characteristics and parameters values is dominant in interpretation of resulting data and it is use to select the properly geophysical method or technique .
There is neither a perfect geophysical method nor any universal algorithm to apply a technology of data acquisition. Using two or more complementary methods always the final solution will be better. Also the experience of interpreter can make the difference specially when natural and artificial factors are integrated to produce higher complexity of situation.
Using different methods Geomathics One can produce relevant images of buried structures and their geological context, very usefull before starting any investment.
Our own equipment allows us to perform a lot of investigations based on the following methods : resistivities and IP –ERT, at a depth up to 70-80 m, resistivities and IP –VES, using high power transmitter, at a depth up to 400 m, SP (self potential), high resolution magnetic measurement on total magnetic field, horizontal and vertical gradients, susceptibility, radiometric measurements, measurements on piezometric surface and some physio-chemical parameters of groundwater .
We long time experienced to use some electromagnetic methods (MT-Magnetotelluric, AMT-Audiomagnetotelluric, CSAMT-Controlled Source Audiomagnetotelluric ) able to investigate deeper structures such as porous reservoirs bearing hydrocarbons or thermal water. We also can use radar, for shallow depth targets, if the requested conditions are fulfilled. For these last methods our external partners supply us with the necessary equipments.
