Determining effective permeability at reservoir scale: Application of critical path analysis

Determining the effective permeability (k(eff)) of geological formations has broad applications to site remediation, aquifer discharge or recharge, hydrocarbon production, and enhanced oil recovery. The objectives of this study are: (1) to explore an approach to estimating k(eff) at the reservoir scale using the critical path analysis (CPA), (2) to evaluate the accuracy of this new approach by comparing the estimated k(eff) to the numerically simulated effective permeability, and (3) to compare the performance of CPA estimates of k(eff) with estimates by three other models i.e., perturbation theory (PT), effective-medium approximation (EMA), and renormalization group theory (RGT). We construct two- and three-dimensional random (uncorrelated) geologic formations based on permeability measurements from the Borden site and assume that the permeability distribution conforms to the lognormal probability density function over a wide range of means and standard deviations. Comparing k(eff) estimated via CPA to k(eff) values derived from numerical flow simulations indicates that CPA provides accurate estimations in both two and three dimensions over a wide range of heterogeneity levels, similar to RGT. Intermodel comparisons show that although PT and EMA provide reasonable k(eff )estimations in rather homogeneous formations, they substantially overestimate the effective permeability in highly heterogeneous formations.

Automated summary

The study aims to estimate the effective permeability of geological formations using critical path analysis (CPA) and compare its accuracy to numerical simulations and other models. The results show that CPA provides accurate estimations in various heterogeneity levels, similar to renormalization group theory (RGT).