GEOPHYSICAL SERVICES

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What is Geophysics?

Geophysics studies the Earth by non-invasive, quantitative physical methods, particularly seismic (reflection, refraction, surface waves), electrical, electromagnetic, magnetic, gravity, and radioactivity methods.

However, the term often refers to ‘solid earth geophysics’ relying on specific branches like seismology, geothermometry, gravity, atmospheric electricity, terrestrial magnetism, tectonophysics, exploration, engineering, and environmental geophysics. Solid earth geophysics is commonly divided into two main fields of study: (1) global geophysics and (2) exploration geophysics.

Global geophysics involves studies of large-scale problems relating to the Earth’s gross structure and dynamic behavior. Exploration geophysics deals mainly with applications of geophysical techniques to solve geothermal, groundwater, hydrocarbon, and mineral exploration challenges and targets of engineering and environmental interest residing at shallower depths.

The breadth of services Cordillera Geo-Services can perform is extensive. Cordillera Geo-Services has the knowledge and expertise to assist you in your projects. Cordillera Geo-Services offers numerous geophysical exploration services to the energy, environmental, mining, groundwater, natural resources, engineering and construction, and cultural resources sectors. Contact us for a free consultation and cost estimate.

What are the benefits of Geophysical Services?

Geophysics delivers an exclusive window into the Earth’s subsurface as a method of detecting shallow and deep subsurface conditions. Geophysics’ relevancy lies in the tangible and cost-effective benefits it offers.

These Include:

  • Non-destructive, Non-invasive. It is ideal for use in populated areas, such as cities, where many of today’s environmental and engineering issues arise. It also means an archaeological or historical site can be examined without destroying it in the process.
  • Cost-effective. Geophysics does not require excavation or direct access to subsurface (except in borehole methods, typically by drilled holes). This means vast volumes of Earth can be evaluated at far less cost than excavation, or even grid-drilling methods would require.
  • Effectiveness. It offers a means of assessing large areas of the subsurface rapidly.
  • Established. The majority of the geophysical techniques have existed for more than a half-century. The techniques are mature but still relatively underutilized and unexplored by decision-makers and project managers who face complex engineering, environmental, and exploration problems.

  • Comprehensiveness. Combining geophysical methods (i.e., multi-disciplinary methods) allows applying different techniques to solve complex problems. The more geophysical properties that are evaluated, the less ambiguous the interpretation becomes.

What Geophysical Service Methods are Available?

The geophysical exploration methods most commonly employed by practitioners include:

  • Seismic Methods: seismic refraction, seismic refraction tomography, MASW, ReMi, seismic tomography, crosshole seismic, and downhole seismic

  • Electrical Methods: electrical resistivity, induced polarization (IP), and self-potential (SP)

  • Ground Penetrating Radar (GPR)

  • Electromagnetics (shallow and deep)

  • Seismoelectrics

  • Magnetics

  • Gravity

  • Borehole Geophysical Logging

How are Geophysical Exploration Methods Applied?

The application of geophysical exploration methods is an organized procedure (“a planned activity”) consisting of several key factors that need to be addressed before work can commence, including:

  • Initial assessment of the suspected problem at hand (I.e., what initial information is known about the site, what additional information is required, and the desired outcomes).
  • Identification of the scope of the necessary geophysical coverage.
  • Determination of which geophysical method or combination of techniques will yield the optimal results. Not all geophysical methods are applicable. Therefore, it is critical to carefully evaluate which methods are most likely to provide data and information pertinent to the problem of interest.
  • Assess how the data and information are acquired, interpreted, and presented to address the problem at hand.
    Once these fundamental elements have been addressed and the project approved, the geophysical survey can commence. Commonly, geophysical field surveys are conducted along oriented lines or survey grids deployed over the area of interest.

How are Geophysical Data and Information Analyzed and Interpreted?

Typically, geophysical data progress through a “life-cycle” consisting of the following stages:

  • Setup: Establishes the geoscience objectives, considers the conventional practice, and identifies how geophysics might contribute. Setting up the problem depends upon which of the four general task types are involved: locating buried objects, mapping “apparent” physical properties, identifying boundaries where physical property values change, mapping detailed locations and depths of actual physical property values.

  • Properties: This step characterizes materials involved and establishes the likely physical property contrasts in the subsurface. The essential physical properties to consider are density, compressional wave and shear wave velocities, magnetic susceptibility, electrical resistivity (or conductivity), electrical chargeability, dielectric permittivity.
  • Survey design: Determines a suitable geophysical study, designs an effective and efficient field survey and identifies possible sources of error, noise, and misinterpretation. Successful application of geophysical techniques depends upon careful survey design and data acquisition.
  • Data acquisition: Carries out the field survey taking all necessary actions to ensure complete, high quality, and cost-effective data sets. Geophysical data are typically acquired along oriented lines or survey grids deployed over the area of interest. Geophysical data can also be gathered inside boreholes using ground-based systems or by aircraft.
  • Data processing: Plots the data and applies appropriate processing, inversion, and analysis. In nearly all cases, interpretation can not proceed until some form of data processing or data inversion is completed.
  • Interpretation: This step focuses on interpreting the results in terms of geological, environmental, or geotechnical objectives. Conclusions are drawn from the geophysical data. Two types of conclusions are introduced, the first being an understanding of physical property distributions and the second being a geological understanding derived from models of physical property distributions.
  • Synthesis: This step seeks to correlate the geophysical data and information with prior and alternative information.

Ultimately, the objective is to develop an integrated presentation of all available geoscientific data and information that can be used for decision-making, establishing time-indexed baseline information, or other purposes. The archival of the geophysical data and information is crucial for future access. For instance, results may be required for reference in future activities such as re-measurements to compare the evolution of conditions over time or for legislative or judicial procedures.

Geophysical Applications

The breadth of services we can perform is extensive. Cordillera Geo-Services has the knowledge and expertise to solve most any geo-sciences challenge you face. Contact us for your free initial consultation and estimate. CGS offers the geophysical services listed below

Geological problems

  • Caves, voids, and sinkhole detection

  • Subsidence, cavity, and karst mapping

  • Bedrock profiling

  • Shallow geological mapping

  • Locating fractures, faults, and other shallow subsurface structures

Archaeological and Forensic problems

  • Archaeological investigations

  • Excavation planning

  • Unmarked grave locations

  • New cemetery plot layouts

  • Geoarchaeological surveys

  • Geomorphic investigations

  • Forensic evidence locating

Geothermal problems

  • Exploration

    • Shallow
    • Deep

  • Operations (in Developing and Producing Geothermal Fields):

    • Porosity mapping within carbonate reservoirs
      • Image hot/cold section of reservoir
      • Monitoring purposes: flood front (steam, water, and CO2), fluid injection and migration in reservoir, and induced-seismicity

Engineering problems

  • Drainage tiles mapping

  • Clandestine tunnel detection

  • Subsurface Utility Engineering (SUE) applications:

    • Locating water lines
    • Metallic and non-metallic utility mapping
  • Construction applications:

    • Location of buried foundations and basements
    • Void detection
    • Locating beams
    • Bridge deck surveys
    • Floor surveys
  • Concrete applications:

    • Concrete slab scanning and imaging
    • Measure slab thickness
    • Find rebar, post-tension cables, conduits, and non-metallic objects
    • Void detection
    • Clearing of boring locations

Environmental problems

  • Site assessment

  • Landfill, waste pits, and trenches delineation

  • Contaminant plume mapping

  • Shallow water table mapping

  • Mapping groundwater pollution

  • Locating Underground Storage Tanks (UST) and drums

  • Leaking pipeline detection

Mining problems

  • Exploration

    • Mineral resource mapping
    • Precious and base metals
    • Aggregate minerals
    • Geological structural mapping
    • Geological and Geophysical interpretation

  • Operations

    • Heap lach characterization
    • In-situ leaching
    • Mine safety
    • Rock quality mapping

  • Environmental and Reclamation:

    • Acid rock drainage mapping
    • Contaminant source identification
    • Abandoned mine land mapping
For unlisted services, please do not hesitate to contact us