Borehole Logging Analysis
Unfortunately, borehole logging is not an exact science. Measurements from different contractors (and different loggers on different days) vary in quality. If we recognise that the logging sonde is a machine and (given the benefits of modern engineering) that sondes of a particular design should behave in a similar manner, our first goal is precision.
Once precision is achieved, by proper calibration and verification procedures, we can nudge the measurements, where necessary, to achieve an acceptable level of accuracy.
In a typical coal logging operation, where density is usually the key measurement, it is prudent to enforce a rigorous calibration and verification procedure from the outset. This involves base calibration (the differences between calibration and normalisation are not laboured here), site verification and the monthly logging of a test well, which represents the ultimate assurance of log quality.