porosity

Porosity Calculations

Porosity Calculations

pypetrophysics.porosity.porosity_density(rhomatrix, rhofluid, rhobulk, limit_result=False, low_limit=0, high_limit=0.6)

Calculate porosity from a density log

Parameters:
  • rhomatrix (float) –

    Matrix density.

    Typical values:
    Sandstone: 2.65 g/cc Limestone: 2.71 g/cc Dolomite: 2.80 - 2.85 g/cc
  • rhofluid (float) – Fluid density.
  • rhobulk (float) – Bulk density from log measurements
  • limit_result (bool, optional) – Apply limits to the result value. By default False
  • low_limit (int, optional) – Low limit. If value falls below this limit it will be set to this value. By default 0
  • high_limit (float, optional) – High limit. If value falls above this limit it will be set to this value. By default: 0.6
Returns:

  • float
  • Density porosity value in decimal units.
pypetrophysics.porosity.porosity_sonic(dtmatrix, dtfluid, dtlog, method='wyllie', limit_result=False, low_limit=0, high_limit=0.6)

Caculate porosity from a sonic log using either the Wyllie-Time Average equation or Raymer-Hunt-Gardener equation.

Parameters:
  • dtmatrix (float) –

    Matrix slowness.

    Typical values:
    Sandstone: 52-55 us/ft Limestone: 47 us/ft Dolomite: 43 us/ft
  • dtfluid (float) – Fluid slowness.
  • dtlog ([type]) – Slowness (DT) from log measurements.
  • method (string) – Select a method for calculating sonic porosity: “wyllie” - Wyllie Time Average (default) “raymer” - Raymer Hunt Gardner
  • limit_result (bool, optional) – Apply limits to the result value. By default False
  • low_limit (int, optional) – Low limit. If value falls below this limit it will be set to this value. By default 0
  • high_limit (float, optional) – High limit. If value falls above this limit it will be set to this value. By default: 0.6
Returns:

Sonic porosity value in decimal units.
Return type:

float
Raises:

Exception – Raise an exception if method value is not 1 or 2.

References

Wyllie, M.R.J., Gregory, A.R., and Gardner, L.W. 1956. Elastic Wave Velocities in Heterogeneous and Porous Media. Geophysics 21 (1): 41–70. Raymer, L.L., Hunt, E.R., and Gardner, J.S. 1980. An Improved Sonic Transit Time-to-Porosity Transform, paper P. Trans., 1980 Annual Logging Symposium, SPWLA, 1–12.