SIMULATING THE ARCHIE PARAMETERS - COMPUTER-PROGRAM AND EXAMPLE FROM THE PERMIAN STRATA OF WEST TEXAS

R. E. Maute and coworkers have proposed a new method to estimate the Archie parameters (cementation exponent and saturation exponent) by minimizing the error between water saturation measured from core and water saturation computed by the Archie equation. To make this principle applicable utilizing only well-logs, the authors proposed to use a dielectric log and minimize the error (constant m and n method) between measured water saturation (Sxo(dielectric)) and calculated water saturation (Sxo(Archie)). In order to reduce further the error between Sxo (dielectric) and Sxo (Archie), m and n were approximated by mathematical functions (polynomial and Fourier series) to model the vertical variation of m and n in the reservoir (variable m and n method). This variable m and n method based on a Fourier series resulted in the greatest error-reduction when compared to the constant m and n method. After determining m and n values that result in the minimum error between Sxo (dielectric) and Sxo (Archie), these values then can be used to calculate the water saturation in the uninvaded zone (Sw).