MCAL
Schlumbergeryd[US]Micro Caliper
The fine-resolution borehole diameter from the microlog or micro-resistivity pad — a sensitive record of mudcake thickness and small-scale hole rugosity that the main caliper can miss.
- Property
- Borehole Diameter
- Inside Diameter
- Quantity
- length
- yd[US] · link[Cla] · µm · m[Ger] · nm · Mm · yd[Ind37] · link[BnB] · ft[BnB] · 100 ft · yd[Cla] · yd[SeT] · 0.1 ft · ft · link[BnA] · ft[BnA] · ft[GC] · 0.1 ft[US] · 1/64 in · ft[Ind62] · km · 100 km · yd[Ind] · fur[US] · 0.1 yd · chain[SeT] · in · mil · chain[BnB] · mm · yd[Se] · mi · mi[naut] · 1/² ft · ft[Br65] · Gm · Em · rod[US] · fathom · ångström · ft[Cla] · dm · ft[Ind37] · chain · chain[Cla] · link[SeT] · link[US] · ft[US] · chain[Ind37] · link[Se] · yd[Ind75] · hm · m · ft[Ind75] · in[US] · chain[Se] · dam · 1/32 in · ft[Se] · 30 ft · yd[BnA] · fm · chain[BnA] · mi[US] · Tm · link · 10 km · ft[Ind] · ft[SeT] · 10 ft · 0.1 in · yd · 1000 ft · 10 in · pm · chain[US] · cm · 30 m · 1/16 in · yd[BnB] · ft[Br36] · mi[nautUK] · yd[Ind62]
- Typical range
- ~6.2–9.6 gAPI
- inches, near bit size on mudcaked beds
Logging tool
No logging tool is associated with this curve.
Service company
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View Schlumberger mnemonics →What is the MCAL curve?
How it's measured
The spacing of the microlog / micro-resistivity pad arms against the borehole wall gives a high-resolution diameter, responsive to the thin mudcake that builds on permeable zones.
How it's used
Permeable-bed and mudcake detection (micro-caliper reading below bit size), and a standoff and quality check for the pad micro-resistivity curves it accompanies.
Common gotchas
It is a shallow, pad-based diameter — noisy in rugose hole and not a substitute for the main mechanical caliper for hole-volume work. Interpret it alongside the microlog resistivities.
In LAS files
Recorded as MCAL (or HMC) in inches, with the microlog MINV/MNOR curves.
Also seen with MCAL in real logs
Curves that appear alongside MCAL in the same wells across the public corpus.