Analysis of Archie's Parameters Determination Techniques

Abstract

An accurate determination of oil reserve in either undeveloped or in developed reservoirs represents the main task of petrophysicist and reservoir engineer. Input parameters of Archie's water saturation model in clean formation or suitable shaly water saturation model must be determined as accurately as possible. Archie's parameters a, m, and n are the most important parameters to be estimated affecting determination of water saturation, in addition to the empirical constants required for selected empirical shaly water saturation model in case of shaly formations.This article presents a new technique to determine Archie's parameters called 3-D Technique. This technique is based on the three-dimension plot of three parameters; formation water resistivity, water saturation, and formation porosity. A comparison study with conventional technique and CAPE technique is conducted to outline the accuracy level of each technique defining Archie's parameters a, m, and n. Two field examples are given to show the applicability of three techniques and also to demonstrate the impact the uncertainty of Archie's parameters values on the accuracy of calculated water values using Archie's model or shaly water saturation model.

Enhanced characterization of reservoir hydrocarbon components using electromagnetic data attributes

“…The reference parameter fields for the Archie's parameters m and n were generated using unconditional simulation based again on an exponential variogram model with anisotropy axis of 6,500 ft in the xdirection, and 6,200 ft in the y-direction, and are shown in Figure 5 [34]. The parameter values range between 1.6 and 2.4, ranges that are typically encountered for carbonate reservoirs [27], [34], [36].…”

“…Relating electrical conductivity changes to the dynamics in the reservoir has proven to be significantly challenge in particular for carbonate reservoir formations [25]- [27]. While Archie's Law has been the standard relationship in the industry for decades, research [28]- [33] has shown that its parameters may significantly vary for different formations and rock types and hence need to be calibrated or estimated.…”

“…While this typically provides a good representation of the rock-conductivity relationship, it may considerably misrepresent the areas farther away from the wells [34]. Hamada et al [27], [34], [35] presented a laboratory study for retrieving Archie's parameter and its uncertainty on 29 natural carbonate reservoir core plugs at reservoir conditions.…”

“…Although several models for relating conductivity of the rock formations to water saturation and porosity have been proposed [39]- [43], none of them has been able to represent various rock formations in a reservoir and all have exhibited high uncertainties in their model parameters [27], making Archie's law the main petrophysical relationship for relating reservoir parameters to the electrical rock conductivity. The conclusions have however outlined the importance of estimating the parameters for different sections of the reservoir to deliver more accurate resistivity-saturation relationships [27], [34].…”

An approximate hybrid method for modeling of electromagnetic scattering from an underground target

“…Here, n is the saturation exponent and has the common value of 2 in strongly water-wet reservoir rocks. An exact computation of water saturation using modified Archie's law, Equation (2.10) is based on an accurate values of Archie's parameters a, m, and n. Hamada [55] presented three techniques to determine Archie's parameters. Other modifications of Archie's law can be found, e.g.…”