ILM
SchlumbergerΩ·cmMedium Induction Resistivity
The medium-depth induction resistivity, reading between the flushed and virgin zones. Compared against ILD and a shallow curve, it profiles invasion and helps correct the deep reading toward true resistivity.
- Property
- Medium Induction Resistivity
- Medium Resistivity
- Quantity
- electrical resistivity
- Ω·cm · kΩ·m · Ω·m²/m · nΩ·mm²/m · Ω·m · nΩ·mil²/ft
- Typical range
- ~1.3–250.8 ohm·m
- ohm·m, invaded-to-transition zone
Logging tool
No logging tool is associated with this curve.
Service company
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How it's measured
Induction coils with a shallower geometric response than the deep array sense conductivity in a zone partway into the formation, inverted to resistivity.
How it's used
The middle member of the induction triad — ILM versus ILD separation quantifies invasion, refines Rt, and flags moved fluids. It combines with a shallow curve for full radial profiling.
Common gotchas
It reads a mix of invaded and virgin rock, so it is neither Rxo nor Rt — interpret it only alongside the deep and shallow curves. The usual induction limits apply in salty muds and at high resistivity.
In LAS files
Recorded as ILM (or RILM, AT30/AT60) in ohm·m, always with ILD.
Also seen with ILM in real logs
Curves that appear alongside ILM in the same wells across the public corpus.