Geophysical Logging - Idaho National Laboratory

Science Center Objects

Our scientists collect geophysical data from wells to understand the character of rocks and fluids below the surface. Geophysical data for a well are recorded, interpreted, and then disseminated as a geophysical log. Engineers and well drillers use geophysical logs to make well construction decisions such as design for well casing, well screen, and pump placement. Hydrologists, geologists and others use geophysical logs to find solutions to problems in groundwater hydrology.

Geophysical logging tools use various sensors (see below) to collect data. Each sensor response is transmitted to logging equipment at land surface. The response is recorded and plotted to produce a log trace; changes in sensor response along the depth of a well tell a story. Certain geophysical logging sensors respond to stratigraphic changes while other sensors respond to changes in groundwater fluids. In general, logging tools include multiple sensors to reduce logging time.

Our staff has extensive experience collecting and interpreting geophysical data both in fractured rock and sediment aquifer systems.

OUR GEOPHYSICAL LOGGING EQUIPMENT

In general, our geophysical logging system depth capacity is 3,200 ft and most geophysical logging tools incorporate multiple sensors.

Natural gamma: to measure changes in background gamma activity

  • Application: Stratigraphic correlation and lithology
  • Logging tool(s): 9057, 9055, 0024, 9042, 9074, 9041, 9055
  • Specifications: Nal scintillation detector
  • Comments: Natural gamma is collected on multiparameter logging tools; typically used to align depth from different logging tool runs.

Neutron: to measure neutron flux attenuation

  • Application: Saturated porosity, UZ moisture content, lithology
  • Logging tool(s): 9057, 9055
  • Specifications: He3 detector, 1.0 Curie, Am-241/Be source
  • Comments: USGS INL Project Office requires borehole casing

Gamma gamma: to measure omni-directional, non-focused density

  • Application: Apparent density changes, lithology
  • Logging tool(s): 0024
  • Specifications: Nal scintillation detector(s)
  • Comments: USGS INL Project Office requires borehole casing

Flow: to measure vertical borehole flow

  • Application: Entry and exit points for flow
  • Logging tool(s): 9721
  • Specifications: EM flowmeter
  • Comments: Requires additional setup time; ambient and stressed conditions generally tested

Temperature: to measure borehole fluid temperature and fluid specific conductance

  • Application: Borehole flow and changes in water quality
  • Logging tool(s): 9042, 9057, 9041, 9721 
  • Specifications: Fluid column temperature
  • Comments: Generally logged within uncased wells filled with conductive fluid

Normal resistivity: to measure formation resistivity

  • Application: Lithology and porosity
  • Logging tool(s): 9057, 9041
  • Specifications: 16N and 64N
  • Comments: Generally logged within uncased wells filled with conductive fluid

Spontaneous potential: to measure electrical potential between borehole and grounded surface voltage

  • Application: Changes in rock properties and water quality
  • Logging tool(s): 9057, 9055, 9041
  • Specifications: Fluid column electric potential
  • Comments:Generally logged within uncased wells filled with conductive fluid

Single-point resistance: to measure resistance of rock and saturating fluid

  • Application: Determination of lithology, water quality, and fracture zones
  • Logging tool(s): 9057, 9055, 9041
  • Specifications: Electrical resistance from points within borehole to electrical ground at land surface
  • Comments: Generally logged within uncased wells filled with conductive fluid

Fluid resistivity: to measure borehole fluid resistivity

  • Application: Borehole flow and changes in water quality
  • Logging tool(s): 9042, 9041, 9721
  • Specifications: Fluid column measurement
  • Comments: Generally logged within uncased wells filled with conductive fluid

Caliper: to measure borehole diameter

  • Application: Fracture identification, hole-diameter corrections, borehole volume
  • Logging tool(s): 9074, 8074, 9065
  • Specifications: Three arm caliper
  • Comments: Caliper data help explain data anomalies where diameter change influence tool response.

Gyroscope borehole deviation: to measure borehole deviation

  • Application: Measures change in horizontal deviation from vertical
  • Logging tool(s): 9095
  • Specifications: Measures deviation where magnetic rocks occur
  • Comments: Requires extra setup time; wells over 1,000 feet require addition drift stations

Downhole fluid sampler: to measure groundwater quality

  • Application: tool has electronically controlled valve that enables collection of groundwater samples at pre-selected depths
  • Logging tool(s): 9750
  • Specifications: Groundwater thief samples
  • Comments: Samples 0.25 gallons per run; multiple runs may be required

Acoustic televiewer: to measure strike and dip of bedding; location, orientation, and character fractures

  • Application: Determination of preferential orientation and frequency of fractures along borehole wall
  • Logging tool(s): 9804
  • Specifications: Records high-resolution, magnetically oriented acoustic reflectivity images of borehole wall
  • Comments: Purchased new tool in 2015

INL Geophysical Logs

You can access our geophysical log data via the USGS GeoLog Locator.