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| Services : Geophysical Methods |
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| Geophysical Methods |
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The Electro resistivity (ER) employs an artificial source of continuous electrical current (I) or very low frequency (or a few fractions of Hz), which is introduced into the soil through a pair of electrodes. The difference in the potential (∆V) that is established in response to this injection can be measured by two other electrodes located nearby. The most significant physical property of the material composition of the subsoil is the resistivity "ρ", inversely proportional to the electrical conductivity "σ”. The techniques of acquisition may be drilling, walking and logging. The main ones are: electric vertical drilling (SEV) one-dimensional (1D) and a walking with dipole-dipole array (CE-DD) two-dimensional (2D), and also three-dimensional acquisitions (3D). The resolution and depth depend on the array and the spacing between the electrodes used in the surface.
Applications:
a) Geotechnical Engineering (to find cavities, faults, cracks, galleries, depth of the non-weathered rock, etc).
b) Economic Geology (mineral exploration).
c) Hydrogeology (water table level and intrusion of saline wedges).
d) Structural Geology (to detect faults and fractures).
e) Stratigraphy.
f) Environmental Study (to delineate deposits of domestic waste and / or industrial, and their contamination plume).
Ground Penetrating Radar (GPR)
The Ground Penetrating Radar (GPR) is a geophysical tool that uses pulses of electromagnetic waves at high frequencies, typically in the range of 10 to 2,500 MHz, known as radio waves. The most significant physical property of the material composition of the subsurface is the electric permissiveness "ε". The acquisition of GPR data can be done in rivers, on areas of land or by logs in two-dimensional (2D) and three-dimensional (3D) manners. The radar has been used for surveys of high resolution with detection of features on the order of a few centimeters to several meters.
Applications:
a) Hydrogeology (mapping of aquifer water table, location of paleo channels, saline intrusion in coastal areas and siltation).
b) Geotechnical Engineering (location of pipes, buried tanks, detection of fractures in tunnels, checking the conditions of the asphalt bed, checking the building foundations and underground cavities).
c) Military applications.
d) Criminal (location of corpses).
e) Archeology from the identification of buildings and / or archaeological (Sambaqui, utensils, etc).
f) Geological Sciences, in situations of little depth. Researching the thickness of soil, depths and heterogeneities of shallow basement, location of mining horizons, among others, in addition to the analysis of facies and sedimentology for the recent deposits and for the old ones.
g) Exploration and evaluation of peatlands.
h) Petroleum Geology (similar characterization of the reservoir).
i) Environmental Study (detection of contaminants plumes in groundwater aquifers).
j) Economic Geology (mapping of fractures in ornamental granite quarries and caves in the limestone quarries). |
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Para mais informações entre em contato:
galencar@sttg.com.br |
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Stratageo Soluções Tecnológicas Ltda
Rua Visconde de Ouro Preto 5, 7º andar, Botafogo
Rio de Janeiro RJ Brasil |
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