Geophysical Logs

This database contains geophysical logs collected from wells in South Carolina.

Overview

This database contains digital geophysical logs that were made of water wells in the State of South Carolina. Geophysical logs are continuous records of the electrical, nuclear, and chemical properties of the sediment, rock, and formation water penetrated by a well. Most of the logs were made by the South Carolina Department of Natural Resources (SCDNR), which owns and operates a geophysical logger, and by its predecessor, the South Carolina Water Resources Commission (SCWRC). Logs were also made by the U.S. Geological Survey (USGS) and by several commercial logging companies.

Logs are obtained from water wells for many different reasons. The primary use of logs is to identify water-bearing zones in the subsurface that can be used as a source of ground water for municipal, commercial, agricultural, industrial, and domestic supplies. Other uses of the logs include:

  • identifying the freshwater/saltwater interface in aquifers along the coast that are being intruded by seawater
  • determining well depth and well diameter
  • pinpointing the depths of well screens
  • locating high-radiation zones that may be contaminating ground water
  • identifying contacts between geologic formations
  • quantifying flow rates in open-hole wells
  • estimating lithology and ground-water salinity, and measuring ground-water temperature.

An excellent source of information detailing the principals and interpretation of geophysical logs is: Keys, W. S. and MacCary, L. M., 1981, Application of borehole geophysics to water-resources investigations: U.S. Geological Survey Techniques of Water-Resources Investigations, Chapter E1, Book 2, 126 p.

Types of Geophysical Logs in the Database

Geophysical Log Units
Caliper (CAL) Inches (IN)
Temperature (TEMP) Celsius (C)
Fluid Resistivity (FLR) Ohm-meters (OHM-M)
Gamma-Ray (GR) Counts per second (CPS)
Single-Point Resistance (R) Ohms (OHMS)
Spontaneous Potential (SP) Millivolts (MV)
16-Inch Short Normal Resistivity (SN) Ohm-meters (OHM-M)
64-Inch Long Normal Resistivity (LN) Ohm-meters (OHM-M)
72-Inch Lateral Resistivity (LAT) Ohm-meters (OHM-M)

Contact Information

For additional information, contact Andy Wachob (wachoba@dnr.sc.gov).