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Objective

The Porosity Interpretation module provides several methods for determining the total and effective porosity.

Key Parameters

The various porosity calculation methods use different parameters that can be set on a zone-by-one basis. Parameter visibility is based on porosity method selection. Parameters set zone-by-zone include:

  • Porosity method: Specify the porosity method to be used
  • RhoB clean1: Bulk density of matrix; shared with clay volume method (Density porosity method).
  • RhoB matrix: Bulk density of matrix visible if Split RhoB Matrix and RhoB clean1 enabled (Density porosity method).
  • DT matrix: Compressional sonic value of the matrix (Sonic porosity method).
  • DT shale: Compressional sonic value of shale (Sonic porosity method).
  • TOC Correction:

Parameters that operate across zones are:

  • Rho fluid: Bulk density value of the fluid.
  • DT water: Compressional sonic value of the fluid.
  • Clay porosity: Shale porosity for total to effective porosity calculation.
  • Phi Max: Maximum allowable porosity.
  • Kerogen density: Bulk density value of kerogen for TOC correction.
  • Nphi Kerogen: Neutron value of kerogen for TOC correction.
  • Sphi Kerogen: Compressional sonic value of kerogen for TOC correction.
  • Split RhoB Matrix and RhoB Clean1: Allow different RhoB matrix parameters between Clay Volume and Porosity Interpretation modules.

Output Curves

  • PHIT: Total porosity from the selected method.
  • PHIE: Effective porosity.
  • DEN_POROSITY: Total porosity from density porosity method.
  • ND_POROSITY: Total porosity from neutron-density method.
  • SON_POROSITY: Total porosity from the sonic porosity method.
  • MINV_POROSITY: Total porosity from the mineral inversion porosity.
  • MINV_POROSITY_STRICT: Total porosity from the sum of the fluids in mineral inversion.

CPI Config Reference

The relevant configuration file is 08_porosity.yaml.

Display

  1. Gamma ray – SP track.
  2. Depth track.
  3. Resistivity track.
  4. Neutron-density track.
  5. Sonic track
  6. Clay volume track.
  7. Grain density track.
  8. Total and effective porosity track.

Associated cross-plots

None.

Associated maps

  • Avg_phit: Average total porosity for the selected zone.
  • Avg_phie: Average effective porosity for the selected zone.
  • PhiT_net_res: Average total porosity for the selected zone in intervals flagged as net reservoir.
  • PhiE_net_res: Average effective porosity for the selected zone in intervals flagged as net reservoir.
  • PhiT_net_res: Average total porosity for the selected zone in intervals flagged as net pay.
  • PhiE_net_res: Average effective porosity for the selected zone in intervals flagged as net pay.

Recommendations

  • When using the porosity from the mineral inversion remember to select either mineral inversion porosity or mineral inversion porosity (strict) options.
  • Make sure to adjust the clay porosity to a value suitable for the reservoir being analyzed.
  • Adjust the maximum porosity when working in areas with higher porosity to avoid accidentally restricting values.
Categories: HelpPetrophysics