Distortion of the Estimated Hydraulic Conductivity from a Hydraulic Test in Fractured Rock Due to Excessive Injection or Extraction

Abstract

In this study, we discussed distortion of the estimated hydraulic conductivity from a hydraulic test due to excessive injection or extraction of groundwater by evaluating the influence of nonlinear flow. Pulse, slug, and constant head withdrawal tests with various head displacements were conducted in fractured granite rock, and the changes of representative Reynolds numbers (Re) during the tests were calculated. The Forchheimer equation and cubic law were used to evaluate the influence of nonlinear flow on the hydraulic tests, and thus the possibility of distortion of the estimated hydraulic conductivity. Our results showed that there was little possibility that nonlinear flow occurred during the pulse tests in the test zones. In the slug tests at several test zones, however, the estimated hydraulic conductivities were likely to be distorted due to nonlinear flow. Except for the test zones with low permeability, the scale effects of the estimated hydraulic conductivities from different types of tests were observed. These results indicated that the scale effect and distortion of the hydraulic parameters can be evaluated by conducting various types of hydraulic tests.