ABSTRACT

: A new method to determine both the hydraulic conductivity and the storage coefficient by simultaneous measurements of fluid pressure and strains is presented. In this study, a new endplug with a built-in, air-actuated valve to control pore pressure inside the sample was developed to accurately measure the poroelastic parameters. Our experimental assembly significantly reduces the extra volume of the pore-fluid system and makes it easy to change the pore-fluid boundary conditions. Three-dimensional storage coefficient was calculated from the volumetric poroelastic parameters obtained from quasi-static strain data, and the hydraulic conductivity was obtained from the transient pore pressure diffusion data. Transient strain behavior during the pore pressure diffusion stage was used to self-check the accuracy of the poroelastic parameters.

1 INTRODUCTION

Hydraulic conductivity and storage coefficients are two parameters which are necessary to analyze fluid flow through porous media. There has been extensive research and discussion on the laboratory measurement of hydraulic conductivity and storage coefficient (specific storage) of geological materials. One important method is the transient pulse method (Neuzil et al. 1981, Wang & Hart 1993, Zhang et al. 2000), and the other is using the transient stage of flow-pump experiments (Olsen et al. 1988, Esaki et al. 1996). According to the error estimates for the transient pulse method (Wang & Hart 1993), the storage coefficient is measured much less accurately than the hydraulic conductivity. Also, the transient process of the flow-pump experiments is affected by the storage capacity of the equipment (Esaki et al. 1996), and it is not straightforward to determine the storage coefficient of the porous medium from the experimental pore pressure data (Kameya et al. In press).

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