Characterizing the Gas Permeability of Natural and Synthetic Materials

Abstract

International audienceThe objective of this article is to propose an experimental method to compare the gas permeability of all the different materials used as gas barrier, such as compacted clay liners or geomembranes. This method is based on the falling pressure experiment, allowing the determination of a single coefficient whatever the material tested. This coefficient is the time constant τ, which is obtained by analytical solutions of the simplified equations describing the transport of gas through the material. The domain of validity is specified for porous media, thanks to a numerical solution of the complete equations system. Two applications are presented, showing the applicability of the method on compacted clay liners and on high density polyethylene geomembranes

Shale-Gas Permeability and Diffusivity Inferred by Improved Formulation of Relevant Retention and Transport Mechanisms

“…Inferred by Barral et al (2010), the measured values of p u and p d can be fitted by the following empirical relationships:…”

“…Nevertheless, Eqs. 57 and 58, or an appropriate datasmoothing method can be used when the measured pressure variation data involve significant noise, such as observed in the data of Barral et al (2010).…”

“…The objective of this article is to develop an improved phenomenological model that can be used for accurate determination of the intrinsic permeability and diffusivity of gas in gas-bearing shale samples tested in the laboratory by pressure-pulse decay methods. Several approaches have been reported in the literature on the measurement of gas permeability and/or diffusivity of samples taken from gas-bearing shale formations, such as by the pressure pulse-decay, gas expansion, and gas desorption tests (Brace et al 1968;Hsieh et al 1981;Neuzil et al 1981;Dicker and Smits 1988;Luffel et al 1993;Wu et al 1998;Cui et al 2009;Barral et al 2010). However, theoretical modeling approaches utilized in data interpretation for determination of permeability and diffusivity involved in these studies are usually unsatisfactory because of inadequate representation of the gas retention and/or transport mechanisms under prevailing test and sample conditions.…”

Gas permeability of bentonite barriers: development, construction and testing of a measurement system

“…In this context, the efficiency of clay barriers in controlling gas emissions is an important issue when designing landfill cover layers. The traditional method of determining the gas permeability of clay barriers essentially involves measuring the gas flow through the barrier under steady-state flow (Didier et al, 2000;Bouazza et al, 2002;Bouazza and Vangpaisal, 2003;Vangpaisal and Bouazza, 2004;Rouf et al, 2016). Although the analysis of the data from the application of this method is simple, the test equipment to ensure and measure this flow regime is generally considered complex and expensive.…”

“…To overcome these limitations, the transient flow method has emerged as a successful alternative to estimate the hydraulic properties of low permeability materials such as rocks, soils (Haskett et al, 1988;Carles et al, 2007;Barral et al, 2009), concrete (Figg, 1973;Claisse et al, 2003), asphalt coating (Li et al, 2004) and bentonite geocomposite (Mendes et al, 2010;Pitanga et al, 2011).This method is essentially founded on monitoring of system's pressure drop as the gas passes through the permeable barrier. Therefore, compared with the conventional method for measuring permeability in a permanent flow regime, the pressure drop method seems to have advantages such as simplicity, economy and quick results.…”