The borehole geophysics activities can be described under three general topics:

1. Providing calibration facilities for industry, government and universities
2. Demonstrating exploration, mining and geotechnical applications
3. Developing innovative technology for borehole geophysics

Ideally, borehole geophysical logs should be quantitative measurements of physical parameters, instead of just an indication of the presence of high or low values of these parameters. To provide such quantitative logs, probes must be properly calibrated to determine their response in a known, controlled situation such as a physical model or borehole. Development of quantitative calibration methods must take place in conjuction with developments in technology and methodology. For any given application, the methods will usually provide qualitative results at first, followed by technological adjustments which make calibration possible as well as desirable (e.g. the switch from analog recording to digital recording). The feedback from a quantitative measurement capability results in changes in methodology, or even in the hardware. This feedback process continues between the applications, and the calibration facilities and procedures until an established methodology for quantitative measurements is developed and widely accepted.

There are currently calibration activities at the GSC in support of quantitative measurements of the following:

On the recommendation of the International Atomic Energy Agency (IAEA), the GSC has also led an international project to cross reference gamma-ray calibration facilities around the world.

The GSC-developed R&D logging system has demonstrated the application of borehole geophysics to minerals and geotechnical problems from coast to coast in Canada. The GSC has studied a broad diversity of applications of borehole geophysics since 1974.

Borehole applications which have been targeted for examination encompass both mineral exploration in mining districts across Canada and geotechnical problems. Applications include:

• delineating mineralized zones, identifying and mapping alteration associated with mineralization,
• lithologic interpretation and hole-to-hole stratigraphic correlation,
• in situ assaying of mineralization,

• determining in situ physical rock properties for use in the interpretation of ground and airborne geophysical data,
• detecting groundwater flow patterns within the holes,
• and groundwater energy research.

Work has been done to characterize physical properties of mineral deposits of tin, lead, graphite, gold, coal, iron, and others.

These are the logging methods currently in routine use at the GSC.

The GSC attempts to push the leading edge of technology to increase the capability of extracting useful information from borehole geophysical measurements. In doing this, often new commercially developed technology (eg. borehole VLF and 3-component Mag) which is not yet widely used is applied to a variety of geological problems.

The technology and methodology mentioned in the table above are generally more advanced versions than those commonly available off the shelf. Some characteristics of some of these "advanced" methods are briefly described below, including both technology and methodology.

1. The high sensitivity temperature probe can measure to less than one ten-thousandth of a degree Celsius (°C), which is about two orders of magnitude more sensitive than commonly used probes.
2. The IP system measures the full waveform digitized every 4 milliseconds, whereas most systems record a maximum of 8 windows in the decay waveform during the 'off time'.
3. The gamma ray logs are from a spectrometric system with full spetral recording which provides information seperately on natural radioactive isotopes of K, U and Th.
4. The density logs are also based on a spectrometric system which not only provides density but also is a heavy element indicator which can be calibrated for assaying.
5. The mise-à-la-masse method, long established for use in conductive deposits, is being used for a wide variety of new applications where conductivity contrasts exist.
6. The VLF logs include inphase and quadrature mesurements of the E field and the three components of the H field.
7. The magnetometer logs are measurements of the 3 components of the earth's magnetic field and forms part of the measurements of the borehole orientation in combination with solid state tilt sensors.
8. With respect to methodology, optimization of parameters for gamma-ray logging and IP logging have been investigated.