Contact Sales
Sign Up Log In

Sw Interpretations Module

PetrophysicsJuly 30, 2025

Objective

The Sw Interpretations Module provides several methods for calculating the water.

Key Parameters

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

  • Saturation method: Specify the water saturation method.
  • Rw at surface: The formation water resistivity at the stated surface temperature.
  • a: Tortuosity factor.
  • m: Cementation exponent.
  • n: Saturation exponent.
  • Rt clay: Clay resistivity.
  • Rwb at surface: Resistivity of bound water at stated surface temperature.
  • Qv: Cation exchange coefficient for total pore volume.
  • Permeability method: Specify the permeability calculate method.

The following parameters operate across zones:

  • Surface Temp: Surface temperature at location.
  • Geothermal gradient: Geothermal gradient at location.
  • Variable m: Determine m-value from Shell method.

Output Curves

Most important curves shown in bold.

  • SW: Water saturation calculated via the specified method. Can be total or effective depending on method selected.
  • SWT: Total water saturation.
  • SWE: Effective water saturation.
  • PERM_FINAL: Permeability.

CPI Config Reference

The relevant configuration file is 09_saturation.yaml.

Display

  1. Gamma ray – SP track.
  2. Depth track
  3. Resistivity track with Rt clay parameter overlay line.
  4. Resistivity track with Rwb parameter overlay line.
  5. Neutron-density track.
  6. Clay volume track.
  7. Porosity track with bulk volumes.
  8. Permeability result track.
  9. Rw-apparent track with Rw parameter overlay line.
  10. Water saturation results line.

Associated cross-plots

  • Pickett cross-plot
  • Buckles cross-plot
  • Rt-Clay cross-plot

Associated maps

  • Avg_sw: Average water saturation for the selected zone.
  • Sw_net_res: Average water saturation for the selected zone in intervals flagged as net reservoir.
  • Sw_net_res: Average water saturation for the selected zone in intervals flagged as net pay.

Recommendations

  • Set all parameters for the water saturation calculation before performing the permeability calculation as many permeability methods use water saturation as an input.
  • Remember that if you select a “PhiE” method for the water saturation calculation, Sw = Swe. Similarly, if you select a “PhiT” method for the water saturation calculation, Sw = SwT.

Tags

Related Insights

DCA

DCA: Type well curves

In this video I demonstrate how to generate a well set filtered by a number of criteria and generate a multi-well type curve. Before starting this video you should already know how to load your data and create a DCA project. If not, please review those videos. Type well curves are generated by creating a decline that represents data from multiple wells.

July 29, 2025
DCA

DCA: Loading Production data

In this video I demonstrate how to load production and well header data for use in a decline curve analysis project. The first step is to gather your data. You’ll need: Production data – this can be in CSV, Excel, or IHS 298 formats. For spreadsheet formats you’ll need columns for API, Date, Oil, Gas, Water (optional), and days of production for that period (optional). Well header data – this can be in CSV, Excel, or IHS 297 formats.

July 29, 2025
General

Sample data to get started

Need some sample data to get started? The files below are from data made public by the Wyoming Oil and Gas Commission. These will allow you to get started with petrophysics, mapping, and decline curve analysis. Well header data Formation tops data Deviation survey data Well log data (las files) Production data (csv) or (excel) Wyoming counties shapefile and projection Wyoming townships shapefile and projection Haven’t found the help guide that you are looking for?

July 9, 2025by Cameron Snow

Get a Personal Demo

Unlock the subsurface with Danomics