SPWLA Glossary

(1) A well-log grid scaled in logarithmic divisions. Usually used with resistivity logs. The use of the logarithmic grid serves to enhance resolution or magnify resistivity readings in the low-resistivity range and eliminates the need for back-up galvanometers and associated curves in the high-resistivity range. Permits the use of overlay techniques in the solution of some exponential relationships.

(2) On the API log grid, tracks 2 and 3 of the grid are divided usually into 4 logarithmic cycles and the grid lines follow logarithmic scales. See scale for illustration.