How to solve the logging problem of the fine cuttings drilled by PDC bits has become the focus that has been paid close attention to by the geological logging persons.

Distinguishing lithologies of the small core samples through measuring their GR values on the ground.;

The deposit is controlled by fanlt and stratigraphy,principly bounded to the sheared zone which formed in a sequence of fine lithic tufls and carbonaceous shale in the contact zone between the tuffaceous and the andesitic sequence within Nafirdeib series.