Calibration of gamma-ray lithodensity logging tool with the correlated sampling feature of McLDL code

The calibration of gamma-ray lithodensity logging tool by using the specific purpose McLDL code has been investigated. The capability of providing complete composition and/or density correlated sampling makes the code appropriate for this calibration purpose. This is accomplished in practice by forcing exactly the same path of the gamma-ray as is taken in the reference sample in a number (up to 10 in the present code) of comparison samples and then adjusting the weights accordingly. Use of a single experimental total response for each lithology at a known composition and density as a reference sample, correlated sampling, resulted in an accurate density calibration curve. This approach will be useful in filling out calibration curves when only a few experimental values are available, and it also reduces the computing time by about one order of magnitude.