Abstract
The characterization of heterogeneous porous rocks is an important task for many applications, including aquifer management, oil field development and environmental protection. When applying the traditional approaches based on single-well hydraulic tests to estimate the hydraulic parameters of porous formations, the estimation is often erroneous. The main reason of the failure is that all these single-well methods assume that the subsurface system can be represented by one or at most a few isotropic homogeneous hydraulic units. However, in reality preferential flow directions often occur in natural porous systems due to the presence of complex depositional geometries. Thus, significant permeability anisotropy exists. To achieve an enhanced characterization, hydraulic interpretation approaches based on information from multiple testing wells are required. In this work, we present a review and comparative study of five methods for detecting aquifer anisotropy. Depending on the formulation, either based on analytical calculations or graphical fittings, their utilizations are of different levels of complexity. To make quantitative comparison, the various methods are applied to analyze synthetically porous media with homogeneous anisotropic transmissivities. We discuss the effectiveness (i.e., the accuracy of result) and efficiency (i.e., the time and effort spent why applying the method), and offer a guidance for the selection of optimal method based on a variety of realistic constrains.