Glossary of Geophysical Terms (W,X,Y,Z)

Well log
A record describing geologic formations and well testing or development techniques used during well construction. Often refers to a geophysical well log in which the physical properties of the formations are measured by geophysical tools, E-logs, neutron logs, etc.
Z/A effect
Ratio of the atomic number (Z) to the atomic weight (A), which affects the relation between the response of gammagamma logs and bulk density