Use this geological calculation for a transparent first-pass interpretation of measured rock, soil, fluid, well, stratigraphic, isotopic, geophysical, or seismic data under an explicitly selected model.

Sw

Wetting-phase saturation as a fraction.

Pe

Entry (displacement) pressure in pascals.

Sr

Residual wetting-phase saturation as a fraction.

Lambda

Pore size distribution index lambda.

Evaluate the Brooks-Corey capillary pressure curve Pc = Pe * Se^(-lambda) for a wetting-phase saturation. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Se

Effective saturation Se as a fraction.

Pc

Capillary pressure in pascals.

• Geological models are scale-, site-, method-, and calibration-dependent. Heterogeneity, anisotropy, sampling, diagenesis, pressure-temperature history, instrument response, boundary conditions, and empirical-correlation range can dominate the result.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Compare independent measurements and models, retain units and analytical metadata, propagate uncertainty, and validate interpretations against logs, cores, maps, laboratory data, or field observations.

• Capillary Pressure Van Genuchten Calculator

  Invert the van Genuchten retention curve Se = [1 + (alpha Pc)^n]^(-m), with m = 1 - 1/n, to obtain capillary pressure in pascals.

• Buckley Leverett Front Saturation Calculator

  Find the Buckley-Leverett shock-front water saturation by the Welge tangent construction on a Corey fractional-flow curve.

• Fractional Flow Water Calculator

  Compute the water fractional flow fw from relative permeabilities and viscosities, neglecting gravity and capillary pressure.