Borehole Logging


DMT can provide a wide range of geophysical logging services for hydrogeological studies, lithological identification, structure and fracture mapping, mineral exploration and well completion assessments.

Experience and knowledge are needed to ensure that borehole data are both accurate and repeatable. It is critical to ensure that logging speeds and system setups are appropriate for any given borehole tool. Lack of experience or care can lead to misleading interpretations, skewed resource calculations or worse. DMT has the experience and expertise needed to ensure that boreholes are logged to an extremely high standard of care.

Common borehole tools and a summary of their uses are provided in the following table:
BOREHOOL TOOLUSE
Natural Gamma
  • Can help to define lithology
  • Stratigraphic correlation
  • Assessment of relative sand/silt/clay content
  • Well completion studies
  • Uranium/coal/shale exploration
Magnetic Susceptibility
  • Detects magnetic minerals, which can help to define lithology
  • Formation-water salinity mapping
  • Delineation of altered sequences
Conductivity
  • Can help to define lithology in sections of wells not cased with metal
  • Stratigraphic correlation
  • Can be used to assess relative sand/silt/clay content
Neutron
  • Can help to define lithology
  • Can aid in defining zones of saturated porosity
Gamma-Gamma
  • Can help to define lithology
  • Provides estimates of bulk density, moisture content
Caliper
  • Provides a record of borehole diameter
  • Helps to delineate fracture zones
  • Delineates areas of borehole collapse
  • Provides correction factors for other borehole tools
Full Waveform Sonic
  • Calculation of P and S wave velocities
  • Delineation of zones of saturated porosity
  • Can help to define lithology
  • Estimates of rock strength and elasticity
  • Borehole completing studies: to identify zones of incomplete or inconsistent casing grout
Optical Televiewer
  • Provides an oriented digital image of the borehole wall
  • Fracture delineation, measurement and characterization (strike, dip, aperture size, frequency)
  • Structural and geological information
  • Allows for the identification of layering, fabric, foliation
Acoustic Televiewer
  • Fracture identification and characterization (strike, dip, aperture size, frequency)
  • Rock Integrity / Hardness
  • Identification of layering/fabric/foliation
Resistivity
  • Identification of zones of conductive mineralization
  • Delineation of fracture zones
  • Permeability Profiling
Induced Polarization
  • Permeability estimates
  • Results can show the presence of disseminated sulphides
Temperature / Fluid Resistivity
  • Identification of zones of variable water quality
  • Identification of zones of variable salinity
  • Fracture delineation
  • Assessment of temperature gradient
  • Temperature log provides valuable correction data for other logs
Impeller Flow Meter
  • Delineation of water flow zones
Heat Pulse Flow Meter
  • Delineation of water flow zones: can detect flow at much lower rates than impeller-based probes