Porosity Interpretation Module

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.