Water Saturation Calculator (Archie)

Calculate water saturation in clean formations using Archie's equation. Fundamental petrophysical calculation for hydrocarbon reserve estimation.

Archie Water Saturation Petrophysics

Input Parameters

Log Readings

fraction
ohm-m
ohm-m

Archie Parameters

Typical: 0.6-1.0 (carbonate), 1.0 (sandstone)
Typical: 1.8-2.0 (sandstone), 2.0-2.2 (carbonate)
Typical: 2.0 (most formations)

Quick Presets

Results

Theory & References

Archie's Equation

Sw^n = (a × Rw) / (φ^m × Rt)

  • Sw: Water saturation
  • φ: Porosity
  • Rt: True formation resistivity
  • Rw: Formation water resistivity
  • a, m, n: Rock-dependent constants

Assumptions & Limitations

  • Clean formations: No conductive minerals
  • Water-wet: Water in pore space, not oil-wet
  • Homogeneous: Uniform lithology
  • Not valid: Shaly sands (use Indonesia/Simandoux)