Influence of residual hydraulic gradients on decay curves for one-dimensional hydraulic pulse tests

Abstract

The hydraulic pulse test is widely used to estimate the hydraulic properties of low-permeability porous media. For the test to be valid, and for Darcy's law to be applicable, the communicating pore space must be saturated. It is also customary to saturate the sample by inducing a steady flow rate through the sample and to neglect any residual hydraulic gradients that may be present in the porous solid due to the saturation process. This paper examines the influence of residual hydraulic gradients on the response of the 1-D hydraulic pulse tests by analytically considering several transient states pertaining to pulse testing in the presence of residual hydraulic gradients that can be present immediately following saturation. Typical numerical results illustrate the effects of residual hydraulic gradients that materialize for certain non-dimensional times governed by a variety of factors, most notably the permeability of the porous medium. © 2009 The Authors Journal compilation © 2009 RAS.