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Geophysical Surveys
Sentrum Engineering Services (Pvt) Limited (SES) is one of the leading geophysical consultants in Pakistan as we cover most of the latest geophysical methods to fulfil the requirements of the client. By using state of the art equipment and up to date processing software our Civil Engineers, Geologists, Geophysicists, Hydrologists, Environmentalists, Surveyors, Technicians and other helping hand acquire and process geophysical data in swift manner.
Different types of geophysical surveys are used in last five decades across the globe in different sectors like water studies, archaeology, mineral prospecting, geology, geophysics, environmental studies and so on. The main purpose remains the same as all geophysical surveys demonstrate the systematic information and geophysical data for subsurface studies along with remote investigation of the physical parameters of the near-surface environment.
Since, drilling, digging and tunnelling getting expensive day by day as it needs more resources to discover the subsurface distribution of natural resources. Therefore geophysical survey get more attention due to its low cost, less number of personal involved and more authentic results of underlying strata and other prospects. Other benefits of geophysical investigation includes its swiftness to cover large area in short time with robust results.
We are specialized in the following geophysical surveys in different disciplines.
- Electrical Resistivity Tomography
- Induced Polarization Test
- Crosshole and Downhole Seismic Investigation
- Borehole Geophysical Logging
- Multichannel Analysis of Surface waves (MASW)
- Seismic Refraction survey
- Ground Penetrating Radar
Electrical Resistivity Tomography (ERT)
Electrical resistivity tomography (ERT) is used to study, inspect, identify & detect the following problems; including searching for groundwater, shallow detailed investigations of pollutant plums in the ground, archaeological surveys, waste site deposit monitoring, mapping and monitoring of salty water contamination of groundwater reservoirs, determine basement rock anomalies, landslide monitoring, mineral exploration, geological stratigraphy, locating concrete pipes, geotechnical site characterization on a cliff for a dam construction, dams & levees, borehole tomography, imaging inside tunnels, spring limestone fractures, identifying karst formations under big structures.
Moreover, we are offering different methods like
- Vertical Electrical Sounding (VES) 1D
- ERT 2D
- ERT 3D
which are used to address problems already discussed. Our problem solving team is specialized in using different methods to evaluate the desire problems.
Induced Polarization Test (IP)
Induced polarization test (IP) helps us in shallow and deep mineral exploration, Groundwater prospecting, mining, landfill thickness, determine high moisture content, pockets or lenses of mineralogical clay or ore bodies and localisation of a buried steel water pipe.
Crosshole and Downhole Seismic Investigation
Crosshole and downhole seismic investigation technique is widely used all over the world due to its authenticity by evaluation rock/soil properties. Several geologic features of subsurface is identified e.g. geologic layering, locate faults, fractures, image voids, solution caverns, washouts with the help of tomography.
Borehole Geophysical Logging
For comprehensive and decisive studies of lithology, lithologic contract, structural features, fractures, water-bearing zones, aquifer hydraulic properties, well construction and others are done by borehole geophysical logging. Analysis of multiple geophysical logs and individual logs reflects other pivotal features of the subsurface.
SES is forefront in providing the following services
- Caliper logging
- Gamma Logging
- Resistivity Logging
- Sonic logging
- Well videography
Multichannel Analysis of Surface Waves (MASW)
MASW is a surface wave method usually measure the shear wave velocity variation in the subsurface. Old methods not able to handle the data effectively and results contains more noise and therefore labour intensive. Whereas Multichannel Analysis of Surface Waves is quite vigorous and used all over the world.
MASW method has ability to tolerate the adverse influence from the near-field effects and noise waves and therefore image Vs distribution within soil in robust manner.
Seismic Refraction Survey
The principle is to customize the refraction of seismic waves by the subsurface rock or soil layers to characterize the underground geologic conditions and structures.
We use the tomographic inversion approach (sensitive to horizontal velocity variations) associated with this method to estimate rippability prior to excavation, mapping depth of bedrock and ground water, calculation of elastic modulus (rock quality assessment), thickness of landslides and identification & mapping of faults.
Ground Penetrating Radar
Ground Penetrating Radar (GPR) Surveys used in different field now a days due to its robust techniques. GPR focused on electromagnetic energy to image the subsurface using contrast of electrical properties of target and host material. Different types of GPRs used for different purposes as radar travels at different speeds through different mediums and therefore limit the effective depth range of GPR investigation.
GPR main purpose to identify utilities in the project area before digging. This is done in order to prevent the accidents and work in the safer and cost effective environment.