In 2012, with investments in new technologies and in the staff, added to the professional experience of more than 20 years in geophysics, we accomplished expertise to serve with quality also the services of Borehole Geophysical Logging, focused on projects in the Mining, Groundwater, Environment and Geotechnique areas. Currently, in partnership with DGI Geoscience, it offers several services in this segment.

The Borehole Geophysical Logging is a method capable of generating vertical profiles integrating several geophysical methods in the same point. This technique consists in lowering a probe using a winch until the bottom of a recently finished borehole. On the way up, the probe performs measurements on the walls of the borehole, which can determinate radioactivity, resistivity, magneticity, sonic results and others. After concluding this procedure, a geophysical profile is obtained with the integrated results of all the probes used.
We apply methods which allow us to investigate up to 1500 meters deep:

  • NATURAL GAMMA – Measures variation of natural radioactivity emitted by changes in concentration of radioisotopes. Important for distinguishing rock types, lithological mapping, stratigraphic correlation and detection of alteration zones, uranium estimates and clay mapping.
  • GAMMA-GAMMA DENSITY – Measures rock density as a function of porosity, fluid content and mineralogical composition. Quantitative in-situ density is valuable for ore tonnage and reserve. Calculate rock mechanics such as Bulk Modulus.
  • ELECTRIC RESISTIVITY/SPONTANEOUS POTENTIAL/SINGLE POINT RESISTANCE – Measures the combined electrical resistivity of the rock, soil and pore fluid. Identifies lithology and fracture zones and may provide contaminant identification based on conductivity of pore fluids. SP highs may indicate base metal sulphides, lows – conductive minerals. SPR increases with grain size and decreases with fracturing and/or greater borehole diameter.
  • ACOUSTIC VELOCITY (P AND S WAVE) – Records the full acoustic waveform influenced by the elastic properties of the formation. Aids in calculation of porosity, acoustic impedance, compressional and shear wave velocity, detection of fractures and cement bond logging assessment. Information from compressional, shear and Stoneley waves can be used to calculate mechanical properties.
  • FLUID RESISTIVITY & TEMPERATURE – Measures changes in fluid temperature, and/or resistivity related to fluid flow in the borehole. Temperature gradient can identify water flow through cracks, fracture or shear zones which can aid structural interpretation and identify potential issues early.
  • ARM CALIPER – Three interconnected arms mechanically measure the borehole diameter. Diameter variations are used to evaluate fracturing, lithology changes, competency of rock, and volume calculations (for example, on LD programs). Also used to inspect paste and shotcrete lines.
  • TELEVIEWERS – Allows imaging, identification and orientation of geotechnical and structural features in-situ. Integrated tilt-meters and 3-component magnetometers provide directional information for true feature orientation.
  • ACOUSTIC TELEVIEWER – Provides an oriented acoustic image of the borehole wall. Allows for accurate identification and categorization of fractures which is useful for geotechnical investigations, including mine design, dam construction and stress breakout analysis.
  • OPTICAL TELEVIEWER – Provides an oriented, high-resolution image of the borehole wall. Allows for the identification of bedding, veins, mineralization, lithological contacts and structural geology in boreholes.
  • FLOW METER – Measures the in-situ velocity of fluid in a borehole. Useful for multiple geotechnical and hydrogeological purposes.
  • INDUCTIVE CONDUCTIVITY – Measures the combined conductivity of rock, soil and pore fluid. Inductive method enables logging through PVC casing. Useful for distinguishing lithology and identifying conductive mineralization.
  • INDUCED POLARIZATION – Measures the chargeability of the formation. Useful for detecting disseminated massive sulphides, which will have a higher chargeability compared to their host rock.
  • DESVIO – It allows to define the inclination and azimuth of the hole.
  • COMPONENT MAGNETOMETER – Integrated tilt-meters and 3-component magnetometers provide directional (dip and azimuth) information.
  • GYRO (NORTH SEEKER AND RATE) – Provides accurate directional information (dip and azimuth) in both magnetic and non-magnetic environments. Allows for superior positional accuracy for precise 3D modeling of all borehole information.
  • BOREHOLE RADAR – Detects lithological changes, and major structural features using radar waves. Waves reflect preferentially off of conductive materials, showing contrasts in rock properties.
  • FLUTe – Flexible liners that can be installed to stabilize and seal the borehole against cross contamination. Allow for numerous hydrogeological measurements including flow, transmissivity profiling, locating NAPL sources, mapping dissolved contaminants and hydraulic head distributions.
  • PACKER TESTING – Determines the hydraulic conductivity of rock mass. Used to generate a hydraulic conductivity v depth curve, that is important for the development of accurate ground water models.
  • MAGNETIC SUSCEPTIBILITY – Measures the amount of magnetic minerals contained within a volume of rock, such as magnetite and pyrrhotite. Identifies changes in lithology, degree of homogeneity and may indicate a zone of alteration.
  • NEUTRON POROSITY – Measures the amount of neutrons absorbed by the formation. Calibrated neutron probes enable quantitative porosity measurement; relative (qualitative) neutron logs can be used to define changes in lithology.
  • CEMENT BOND LOGS – Measure the cement bond quality between casing and the formation.

Equipments AFC Geofísica

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