Coal Anisotropic Sorption and Permeability: An Experimental Study

Yulong Chen,Xuelong Li,Bo Li

doi:10.3390/pr6080104

Abstract

Knowledge of the bedding plane properties of coal seams is essential for the coalbed gas production because of their great influence on the inner flow characteristics and sorption features of gas and water. In this study, an experimental study on the anisotropic gas adsorption–desorption and permeability of coal is presented. The results show that during the adsorption–desorption process, an increase in the bedding plane angle of the specimen expands the length and area of the contact surface, thereby increasing the speed and quantity of adsorption and desorption. With an increase in the bedding angle, the number of pores and cracks was found to increase together with the volumetric strain. The evolution of permeability of coal heavily depended on stress–strain stages. The permeability decreased with the increase of stress at the initial compaction and elastic deformation stages, while it increased with the increase of stress at the stages of strain-hardening, softening and residual strength. Initial permeability increased with increasing bedding angle.

Highlights

IntroductionCoalbed gas extraction is a complicated process that is influenced by many factors, such as the mechanical properties of the formation (e.g., modulus, strength), sorptive capability, and transport properties (e.g., diffusivity, permeability) [1]
Coalbed gas extraction has been considered as an attractive solution to control coal-mine disasters and provide new energy, and it has found great success in many countries (e.g., Australia, Canada).Coalbed gas extraction is a complicated process that is influenced by many factors, such as the mechanical properties of the formation, sorptive capability, and transport properties [1]
This study focused focused on onthe theanisotropic anisotropicadsorption–desorption adsorption–desorptionand and permeability coal

Summary

Introduction

Coalbed gas extraction is a complicated process that is influenced by many factors, such as the mechanical properties of the formation (e.g., modulus, strength), sorptive capability, and transport properties (e.g., diffusivity, permeability) [1]. A better understanding of mechanical behavior and transport properties of coal is necessary to optimize field development. Sorption and permeability are the most important parameters to influence gas production in coalbed gas formations [2,3,4]. It is found that coal sorption and permeability is impacted by many factors, such as fracture geometry [11,12,13], stress [14,15,16], water content [17,18], and temperature [19,20]

Methods

Results

Conclusion