What technique is used to measure shale content in geological formations?

Gamma ray logging is the most suitable technique for measuring shale content in geological formations. This method relies on the detection of natural gamma radiation emitted by the formations being investigated. Shale typically contains higher concentrations of radioactive isotopes, such as potassium, thorium, and uranium, compared to other rock types.

In gamma ray logging, a tool is lowered into a borehole to measure the gamma radiation emitted from the surrounding rock. The results are displayed as a continuous log, allowing engineers and geologists to identify intervals with varying shale content based on the recorded gamma ray counts. Higher gamma ray readings correspond to greater amounts of shale, while lower readings indicate the presence of more non-radioactive rock types, such as sandstone or limestone.

This technique provides crucial information for characterizing subsurface geology, guiding drilling and exploration efforts, and informing resource extraction decisions. Other techniques, while useful for gathering different types of data about geological formations, do not provide the specific measurements for shale content that gamma ray logging does.