| Borehole Technique | Use | |
 |
|
|
| Fluid temperature & conductivity | Water supply characterization, fracture location, total dissolved solids estimation | |
| Impeller & heat-pulse flow meters | Water flow rate and direction along the borehole | |
| Acoustic velocity | Mechanical properties, fracture location, rock type estimation, cement bond monitor | |
| Electrical resistivity/IP | Electrical properties and structures, fracture locations, economic mineral locations | |
| Cross-hole seismic & cross-hole radar | Hole-to-hole inspection and detail correlations, local detail structures | |
| Magnetic susceptibility & field strength | Magnetic properties of materials intersected by borehole, geologic characterizations | |
| Inductive electrical conductivity | Mining exploration, waste site characterization | |
| Time Domain EM | Economic mineral exploration, | |
| VLF-EM E & H fields | Reconnaissance exploration, mining, water resources | |
| TV and acoustic TV | Borehole wall inspection, fracture location and oreintation | |
| Gamma-gamma density | Bulk material density surrounding the borehole | |
| Neutron-neutron porosity | Rock lithology, water/hydrocarbon content, porosity | |
| Natural gamma | Natural radioelement concentration of materials in borehole wall | |
| Gyroscopic | Variation of azimuth and dip of borehole with depth along borehole |
Figure 1. A borehole survey in progress.
Figure 2. Borehole log.
Figure 3. VLF-EM survey reconnaissance.
Figure 4. Seismic velocity data from the same borehole as in Figure 3.
Figure 5. Correlation of natural gamma and electrical conductivity responses between two adjacent boreholes drilled in the overburden. These are shallow boreholes. The phase response is proportional to the magnetic susceptibility.