ABSTRACT:

The objective of this paper is to present a new system which can be appropriate for the hydraulic behavior of faults assessment. In this paper an evaluation model, based on combining the Analytic Hierarchy Process (AHP) and the Fuzzy Delphi method (FDM), has been presented for assessing fault hydraulic behavior estimates. This research treats the hydraulic behavior of fault classification as a group decision problem, and applies the fuzzy logic theory as the criterion to calculate the weighting factors. In addition, about 87 faults were selected as the case study examples. After determining the hydraulic behavior of faults for each case, the equivalent permeability of fault zones, according to proposed method, has been estimated. Afterward, the results of actual measurement permeability compared with the estimated permeability, and then the relation and difference between proposed method and actual permeability were discussed. Results show that the proposed method can be used to assess permeability of fault zones.

1 INTRODUCTION

Joints, deformation bands and faults are physical structures in rocks that have developed as tabular zones of localizes strain and fracture in response to tectonic and gravitational loading. The flow properties of faults are in general quite complex, because they can act as conduits or barriers to fluid flow. In most cases, a fault displays both aspects of this complex signature in time and space (Aydin, 2000). The distribution and orientation of these components may be variable within a fault zone, and each component has its own hydraulic properties that vary as functions of geologic, mechanical, and hydrologic condition. Further, the influence of a given structural component on fluid flow within and around a fault zone depends strongly on the component's geometric relationship to other structural components and to the direction of fluid flow (Fig. 2).

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