SPOR
Schlumberger%Sonic Porosity
Porosity derived from sonic slowness via a transit-time-to-porosity transform. An acoustic porosity that, unlike density or neutron, is largely insensitive to gas and tends to read primary (intergranular) porosity.
- Property
- Porosity
- Volume Fraction
- Quantity
- dimensionless
- % · GEuc · ppm · mEuc · cEuc · MEuc · nEuc · pEuc · kEuc · ppk · fEuc · µEuc · dEuc · EEuc · TEuc · Euc
- Typical range
- ~0.2–62 pu
- porosity units, from sonic transit time
Logging tool
No logging tool is associated with this curve.
Service company
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How it's measured
Computed from the compressional slowness with the Wyllie time-average or Raymer-Hunt-Gardner transform, given matrix and fluid transit times.
How it's used
A third porosity for multi-mineral solving, primary-porosity estimation (it tends to ignore vugs and fractures), and a check against density-neutron porosity.
Common gotchas
It depends on the chosen matrix transit time and a compaction correction in unconsolidated sands; it under-reads secondary (vuggy or fracture) porosity and is biased by gas and shale.
In LAS files
Recorded as SPOR (or PHIS, SPHI) in v/v or %. It derives from DT, so it inherits any sonic problems.
Also seen with SPOR in real logs
Curves that appear alongside SPOR in the same wells across the public corpus.