Applied Geophysical & Geotechnical:
Geophysical methods apply physical laws with aid of sophisticated methods and techniques to investigate Earth’s subsurface. It measures variations of physical properties of subsurface rocks using non-invasive and non-destructive techniques.
Surface seismic survey
- Seismic refraction.
- Seismic reflection.
- Seismic refraction tomography (SRT).
- Multi-channel analysis of surface waves (MASW).
- Spectral analysis of surface waves (SASW).
Borehole seismic survey
- Full wave sonic logging.
- Down-hole seismic test.
- P&S wave suspension logging.
- Cross-hole seismic test.
- Cross-hole seismic tomography.
- Electrical resistivity tomography (ERT – 2D & 3D).
- Vertical electrical sounding (VES).
- Spontaneous/Self Potential (SP).
- Shallow direct – current (DC) electrical resistivity sounding.
- Induced polarization (IP).
- Thermal resistivity.
- Frequency Domain EM.
- Time Domain TDEM.
Geophysical Logging Methods
- Three-arm caliper logging.
- Temperature conductivity logging.
- Natural gamma logging.
- Gamma – gamma (density) logging.
- Impeller flow meter logging.
- Electric logging.
- Deviation logging.
- Soil Sampling.
- In-Situ Testing.
- Lab Testing.
The new technology allows Geophysical & Geotechnical methods to cover different important fields like:
- Geo-hazard Assessment
- Geothermal Reservoir Modeling.
- Civil Engineering Investigations.
- Environmental Investigations.
- Hydrogeological Investigations.
- Archeological Investigations.
- Forensic Investigations.
Seismic Reflection, Refraction and MASW Methods:
Generating Seismic waves are generated using source (Sledge Hammer or Accelerator)
Seismic refraction surveys are used to determine:
Bedrock profile, rock quality & depth, identification of geotechnical properties of the subsurface layers (Poisson ratio, Young Modulus, Shear Modulus) ,the presence of fractures and cavities, slope stability studies.
Borehole Seismic Survey:
Cross-hole & Down-hole Seismic Surveys
Cross-hole seismic surveys are used to derive information on the elastic properties of materials between two or more boreholes by measuring travel time of seismic energy depths.
1D/2D/3D Electrical Resistivity Sounding & Tomography:
The electrical methods used for measurement of subsurface resistivity to the induced electric current using DC battery.
The Electrical surveys are used in ground water exploration, determination of underground water resources,bedrock quality & depth measurements,pollution plumes mapping,mineral prospecting, detecting cavities, archaeology, dam structure analysis,and contamination sources detection.
Ground Penetrating Radar (GPR) – (16 – 2600 MHz Frequency):
GPR technology applications include:
Detection & mapping of underground utilities, cavities & voids (structures – dams, bridges, weirs, barrages, etc.), road investigations, , soil – bedrock interface, water table determination, and archeology & forensics, concrete inspection,structural inspection.
Potential Field Methods:
Gravity measurements are used to map density contrasts in geological formations.
It is applied for the following purposes:
Bedrock topography under landfills, mapping large metallic mineral deposits, locating subsurface caverns, as well as cavities.
Magnetometers can be used to map burried variations of magnetic susceptibilities.
It is employed in many applications including:
- Geological Mapping.
- Mineral Exploration.
Magnetometers is used to detect buried ferrous metal objects, or bedrock features with contrasting magnetite content. It is applied for the following applications:
- Location of buried metal objects (e.g., tanks & drums)
- Mineral Exploration
- Determination of sedimentary basins thicknesses.
Geophysical Logging Methods:
Borehole logging provides continuous record of a wide range of formation’s rock properties using geophysical techniques.Determination of rocks and formations elastic properties,resistivity, or radioactivity can be made using geophysical well logging method. It is used to:
- Distinguishing between sands and shales
- Detecting regions where the borehole walls are compromised.