Volume 23, Issue 1 (March 2000)
Evaluation and Application of the Transient-Pulse Technique for Determining the Hydraulic Properties of Low-Permeability Rocks—Part 1: Theoretical Evaluation
The transient-pulse technique is a well-established laboratory method for determining the permeability of hydraulically tight rocks. Although graphical solutions to this test make it possible to evaluate both the permeability and the specific storage of a rock specimen, the attendant procedures are relatively complicated. Often, the expression introduced by Brace et al. (1968) is typically used to interpret the experimental results and arrive at a value for permeability only. In Part 1 of this study, the general solution for the transient-pulse test is extended to consider quantitatively the transient distributions of hydraulic head and hydraulic gradient within the specimen and to examine the validity of using the solution presented by Brace et al. (1968) under these conditions. Based on a series of parametric studies, some theoretical and practical considerations related to the design of a transient-pulse test are also provided. In Part 2, a relatively convenient and general approach to calculating the specific storage of a specimen from a transient-pulse test is presented and its efficiency is demonstrated through the application of this approach to experimental investigations.