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
- Gamma ray – SP track.
- Depth track
- Resistivity track with Rt clay parameter overlay line.
- Resistivity track with Rwb parameter overlay line.
- Neutron-density track.
- Clay volume track.
- Porosity track with bulk volumes.
- Permeability result track.
- Rw-apparent track with Rw parameter overlay line.
- 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.
