Can Any One Tell Me Something About Radioactivity Logs?

The preparation of the radioactivity logs is based on the fact that different types of rocks exhibit the phenomena of radioactivity due to the presence of the radioactive minerals in them and the degree of the radioactivity varies in different rock types. Further it is important to note that the radioactivity of a given stratum or rock type may become its characteristic feature over wide areas due to the remarkable constant value of radioactivity exhibited by that stratum or rock type.

The measurement and recording of variations in the radioactivity of various rock units encountered in a borehole during drilling is termed as radioactivity log. These logs consist of two types of curves on the basis of technique used to record and prepare these logs:
1. Gamma-ray Curve; provides information about the nature of strata penetrated and marks the lithological changes in a drilled hole.

2. Neutron Curve; provides information about the hydrogen bearing fluid contents and hence is indicative of the porosity of the rock.
These logs are usually plotted on the same strip of paper side by side. The gamma-ray curve is plotted on the left of the central line while the neutron curves on the right side of it.