spwla

Functions for computing resistivity from saturation

spwla.resistivity.archie(sw, poro, m, n, a=1)

Compute the formation resistivity.

This function calculate formation resistivity from water saturation, porosity, and Archie’s parameters a, m, and n. The formula for the Archie’s Law is:

Rt = a * poro**m * sw**n

Parameters:

• sw – 1d array. Water saturations.
• poro – 1d array. Formation porosity.
• a – Archie’s parameter, constant.
• m – Archie’s parameter, cementation exponent.
• n – Archie’s parameter, saturation exponent.

Returns:

resistivity – 1d array.

Example

>>> from petrophysics.resistivity import archie
>>> rt = archie(1.0, 0.2, 2, 2, 1)
0.04