General Geophysics

We have decades of expertise in applying the full spectrum of geophysical methods for a wide range of industries. We draw on this expertise to design customized geophysical surveys, for which we then collect, process and interpret geophysical data of the highest quality. Integration of information from complementary datasets is a powerful part of our interpretation workflow that leads to a comprehensive understanding of the targets and their setting.

We provide assistance in coordination with local authorities, safety and security issues.

A wide range of industry applications

Oil & Gas

DC-Resistivity method on seismic

Our experts develop and implement customized ground geophysics solutions for the Oil & Gas industry and specialize in near-surface characterization to mitigate seismic imaging issues.

Near-surface multi-physics studies, integrating land microgravity, DC resistivity and seismic data, deliver effective refraction static corrections leading to a more accurate seismic image of the subsurface and an improved well-to-seismic tie.

Microgravity, 4D time-lapse gravity surveys and continuous gravity monitoring assist reservoir characterization and estimation of reservoir depletion.

Our HSE policy is in total compliance with Oil and Gas standards.

Mining

Mineral Lodes on resistivity map

Reducing risks along the mine lifecycle

Based on our knowledge of the mineral deposits, environments and associations, we select the most appropriate technologies to reduce the risks encountered along the mine lifecycle. For instance, in the planning stage of a new coal mine, gravity, magnetic and resistivity investigations can be performed to get a better understanding of basin geometry, thickness of lithic fill, morphology of the basement/ bedrock, location of sub-basins and detachments, faults and location of dykes.

Unique solutions for every mine

For identification of Kimberlite-Clan-Rocks (KCR) strewn in clusters at the intersections of mantle reaching faults in cratonic areas, we can use gravity and magnetic mapping complemented with resistivity imaging.

To identify uranium and Platinum Group of Metals (PGE), we generally employ gravity and magnetics in association with induced polarization (IP) and time domain electromagnetics (TDEM).

For gold exploration, depending on the host rock environment, the most common technologies used are a suite of resistivity surveys, including induced polarization (IP), surface and borehole time domain electromagnetics (TDEM) and controlled source electromagnetics (CSEM) in case of deep exploration programs.

Inversion of broadband magnetotellurics (MT) data, integrated with other ancillary data, lead to 2D and 3D depth models for reliable answers in the exploration of many minerals, including graphite, hydrothermal magnetite, copper and gold, KCR, magmatic nickel and copper, uranium and volcanogenic massive sulphides (VMS).





Engineering

Tangible deliverables reducing risks

Diffraction generated by a pipe in a 3D GPR volume

To help developers and engineers effectively reduce risks through the lifecycle of their projects, we deliver interpretation of geophysical data that we have previously acquired on site and processed. Our deliverables include:

  • Cavity distribution map for a safe pile planning
  • Ground stiffness evaluation for foundation design
  • Structural imaging for seismic risk evaluation
  • Imaging of cavities, angled fractures and lithological series for railways routes planning using high resolution seismic reflection surveys

Geophysics answering geotechnical challenges

Geophysical methods are selected according to the challenge and prevailing environmental conditions, in addition to the geological data available. Surface and borehole geophysics techniques include:

  • Seismic reflection, seismic refraction and surface wave seismic
  • Microgravity
  • Advanced wireline logging methods
  • Resistivity methods (DC and electromagnetism)
  • High resolution ground penetrating radar (GPR)
  • GPR and electromagnetic methods can be used for pipes detection

Groundwater & Environmental

Assisting search of groundwater

CGG designs geophysical programs specially tailored for groundwater. They provide solutions for:

  • Detection of aquifer zones and cap rocks and estimation of their thickness in a sedimentary terrain
  • Mapping of faults/shears both vertical and sub-horizontal in hard rock (metamorphic terrains) which controls water pools and its movement
  • Detection of perched water tables
  • Differentiate between saline water incursions in near shore area from the fresh water pools
  • Detection of large water resources in solution cavities and in palaeochannels

    Environmental Monitoring

    Environmental monitoring requires accurate identification of existing or potential causes of pollution and the definition of the lithology and quality of shallow strata (mainly the first twenty meters). Thus, precise measurement of geophysical parameters at a generally smaller scale than employed for exploration surveys, are needed.

    DC resistivity and seismic for groundwater exploration

    Micro-gravity surveys have been used to detect land subsidence or areas likely to subside (decompressed terrain and hollows).

    Buried objects are detected by ground-penetrating radar and, in case of metallic buried objects and pipelines, magnetic surveys have been used as well. Gamma ray spectroscopy is used to detect man-made radioactivity and map soil structure. Electromagnetic (EM) and resistivity methods are used most often for mapping groundwater location, salinity and caverns and also to identify electrically resistant pollutants. Multi-physics recordings (tomography, resistivity, radar, micro-gravity) are used to locate pollution rapidly, establish its causes and monitor spreading.

     

  • Geothermal

    High-enthalpy, volcanic-hosted hydrothermal systems are typically characterized by low temperature smectite-dominated clay cap zone above the higher temperature propylytic alteration of the exploitable geothermal reservoir zone below. The smectite cap zone is electrically conductive compared to the propylitic reservoir zone below, and therefore provides an ideal target for inductive electromagnetic (EM) geophysical methods such as time domain electromagnetics (TDEM) and magnetotellurics (MT).

    Depth resistivity section from inverted MT data

    While TDEM surveys are effective in mapping into the conductive cap zone, MT surveys are required to penetrate thick cap zones and map the critical geometry of the interface at the base of the cap zone – normally top reservoir conditions. Structural highs at base of the cap zone generally indicate zones of enhanced vertical permeability below.  MT is therefore recognized as a standard exploration tool in geothermal resource assessment.

    In mid and lower temperature geothermal systems hosted in sedimentary or volcano-sedimentary settings, EM and MT provide tools to track the zones of higher permeability and warm saline outflow. Gravity and magnetics provide structural mapping control, particularly in basin and range type settings where up-flow paths along major fault zones are targeted. Induced polarization (IP) surveys may be useful to distinguish possibly conflicting conductors related to graphite, sulphide or such.

    CGG offers integration of the geophysical survey and ancillary data to provide an improved geothermal concept model rather than anomaly maps and sections alone.



    The Full Spectrum of Geophysical Methods

    Our comprehensive portfolio of methods includes:
    • GPS gravity and microgravity
    • DC Resistivity, Induced Polarisation
    • Magnetics
    • Magnetotellurics
    • GPR (Ground Penetrating Radar)
    • Radiometrics
    • Seismic refraction and high-resolution reflection for near-surface characterization
    • Surface waves inversion
    • Weathering Reflection Surveys (WRS)
    • Shallow well geophysics including: uphole/shallow VSP surveys; wireline logging; cross-well geophysics


    Onshore - General Geophysics - Resistivity

    Resistivity Surveys

    Rely on CGG for using the most appropriate resistivity method among a large spectrum of possibilities

    Onshore - UltraSeis

    UltraSeis

    Enabling quantitative interpretation with high-quality, high-density and cost-effective seismic. A fully integrated solution for onshore reservoir development.

    Equipment -  UNITE

    UNITE

    Get better coverage with the most flexible cableless system. Safely survey sensitive environments. Remotely harvest data without interruption. Seamless cable and cableless integration.

    Onshore (General Geophysics)

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