Chap VII: Borehole geophysics for Hydrogeology and log analysis

Limitations of borehole logging:  Laboratory analysis of core is essential either for direct calibration of logs or for verifying calibration carried out by other means. Calibration of logs for one rock type may not be valid in other rock types, because of how the rock-matrix chemical composition may affect log measurements. For this reason, geophysical logging cannot completely replace sampling. A log analyst cannot evaluate a set of logs properly without information on the local geological and hydrological conditions. To maximize results from logs, at least one core hole should be drilled or core recovered from selected intervals in one borehole at each study site.