1. n. [Formation Evaluation]

A particular type of induction log that was designed to read deep into the formation while maintaining reasonable vertical resolution. The deep induction log (ID) is based on the measurement of a 6FF40 array and was combined with a medium induction array to form the dual induction tool. Versions built after 1968 had a small extra transmitter coil to reduce the borehole effect on the medium induction while changing the deep response very little. The midpoint of the ID integrated radial geometrical factor is at 62 in [157 cm] radius for high resistivities, reducing to 45 in [114 cm] at 1 ohm-m. ID receives very little signal from within 20 in [50 cm] of the tool. The vertical resolution is about 8 ft [2.4 m] but varies with local conditions.

Alternate Form: ID

See related terms: cave effect,  depth of investigation,  dual induction,  geometrical factor