LLD
SchlumbergerΩ·cmDeep Laterolog Resistivity
Deep laterolog resistivity — a focused-current true-resistivity (Rt) measurement built for salt muds and high-resistivity carbonates where induction struggles. It is paired with the shallow laterolog for invasion analysis.
- Property
- Deep Laterolog Resistivity
- Deep Resistivity
- Quantity
- electrical resistivity
- Ω·cm · kΩ·m · Ω·m²/m · nΩ·mm²/m · Ω·m · nΩ·mil²/ft
- Typical range
- ~1.6–614.9 ohm·m
- ohm·m, high in tight carbonates and hydrocarbons
Logging tool
No logging tool is associated with this curve.
Service company
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How it's measured
Guard and bucking electrodes focus a survey current horizontally into the formation, so the current flow (and thus apparent resistivity) reflects the deep formation rather than the borehole. It requires a conductive, water-based mud path.
How it's used
True-resistivity input for saturation in salt muds and hard rock, and — with LLS — invasion and Rt/Rxo profiling. It is preferred over induction at high resistivity.
Common gotchas
It cannot be run in oil-based (non-conductive) mud. The Groningen effect and thin resistive beds distort readings, and deep/shallow separation must be interpreted with invasion in mind.
In LAS files
Recorded as LLD (or RLLD, RD) in ohm·m. Shallow laterolog LLS and micro-resistivity MSFL usually accompany it.
Also seen with LLD in real logs
Curves that appear alongside LLD in the same wells across the public corpus.