Revisiting the methods for gas permeability measurement in tight porous medium

• Main Authors: Diansen Yang, Wei Wang, Weizhong Chen, Xianjun Tan, Lige Wang
• Format: Article
• Language: English
• Published: Elsevier 2019-04-01
• Series: Journal of Rock Mechanics and Geotechnical Engineering
• Online Access: http://www.sciencedirect.com/science/article/pii/S1674775518302919

Permeability is a key parameter to describe fluid transport properties of porous medium; however, the permeability measurement is extremely difficult for tight porous medium, e.g. fine-grained rock or dense soil. In this paper, three methods for gas permeability measurement, i.e. steady state method, pulse decay method (PDM) and pressure oscillation method (POM), are first reviewed and then their advantages and drawbacks are discussed. Both analytical and numerical solutions of gas permeability are presented for the tight porous medium. The results show that the analytical method is relatively simple but only valid under certain conditions, whilst the numerical method is more robust and generic, which can take into account several factors such as porosity, saturation, gas leakage, and unconventional boundary conditions. The influence of the effective porosity on the permeability determination is further analyzed using the proposed numerical method. In this study, new pressure data interpretation procedures for PDM and POM are proposed, and the obtained results can serve as a guidance to define a proper method for permeability measurement of the tight porous medium. Keywords: Permeability measurement, Steady state method, Pulse decay method (PDM), Pressure oscillation method (POM), Effective porosity, Tight porous medium