USGS Ground Water Information
Branch of Geophysics
Table 1. Summary of selected geophysical logging methods
[Relative cost: 1–3 inexpensive to expensive; time: 1–3 fast to slow;
relative difficulty: 1–3 easy to difficult]
| Method | Purpose | Property measured | Cost | Time | Difficulty |
| Caliper | Generate continuous profile of borehole diameter | Borehole diameter | 1 | 1 | 1 |
| Single-point resistance | Delineate changes in lithology, porosity, and (or) clay content of surrounding formation or changes in porosity and total dissolved solids in the formation water | Resistance of formation, fluids in formation, and borehole fluids | 1 | 1 | 1 |
| Normal resistivity | Determine changes in resistivity of the fluids in the formation and (or) lithology | Resistivity of the formation; with additional data, true resistivity can be calculated | 1 | 1 | 1 |
| Electromagnetic Induction | Delineate changes in rock type or in electrical properties of fluids in the rock formation; corroborate surface resistivity surveys | Bulk apparent conductivity of the formation and pore fluids surrounding the borehole | 1 | 2 | 2 |
| Fluid resistivity | Identify differences in concentration of total dissolved solids in borehole fluid; these differences typically indicate sources of water that have come from different transmissive zones | Electrical resistivity of borehole fluid, from which specific conductance is calculated | 1 | 1 | 1 |
| Fluid temperature | Identify where water enters or exits the borehole | Temperature of borehole fluid; differential temperature (rate of change of the temperature) is calculated | 1 | 1 | 1 |
| Heat-pulse, electromagnetic, and spinner flowmeter | Map fluid flow regime and transmissive fractures in the borehole | Direction and magnitude of vertical flow within the borehole | 3 | 3 | 3 |
| Camera | Characterize rock type, identify changes in rock type and small-scale geologic structures, locate and describe fractures, describe borehole construction, and identify problems with borehole integrity and (or) possible signs of contamination | Visual fish-eye view and side-looking view of borehole | 2 | 2 | 2 |
| Acoustic televiewer | Map location and orientation of fractures intersecting borehole and generate a high-resolution acoustic-caliper log | Amplitude and travel time of the reflected acoustic signal | 3 | 3 | 3 |
| Deviation | Three-dimensional geometry of the borehole | Azimuthal direction and the inclination of the borehole | 2 | 2 | 2 |
Modified from:
Johnson, C.D., and Williams, J.H., 2003, Hydraulic logging methods - a summary and field demonstration in Conyers, Rockdale County, Georgia, in ed. Williams, L.J., Methods used to assess the occurrence and availability of ground water in fractured-crystalline bedrock - an excursion into areas of Lithonia Gneiss in eastern metropolitan Atlanta, Georgia: [Atlanta, Georgia], Georgia Geologic Survey, Guidebook 23, p. 40-47.
U.S. Department of the Interior |
U.S. Geological Survey
URL: http://water.usgs.gov/ogw/bgas/logging_table.html
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Page Last Modified: Thursday, 13-Sep-2007 14:25:11 EDT
