Development of a coal shrinkage swelling model accounting for water content in the micropores

Development of a multi-mechanistic, dual-porosity, dual-permeability, numerical flow model for coalbed methane reservoirs

“…These two responses from desorption and effective stress changes have opposing effects on changes in porosity and permeability. A number of permeability models including Sawyer et al (1990), Seidle and Huitt (1995), Palmer and Mansoori (1998), Shi and Durucan (2005) and Thararoop et al (2009) have been proposed to capture the influence of shrinkage and swelling on the permeability of coal. All of the aforementioned models excluding Seidle and Huitt's model incorporate the two conflicting mechanisms.…”

“…All of the aforementioned models excluding Seidle and Huitt's model incorporate the two conflicting mechanisms. In this study, the coal shrinkage and swelling model proposed by Thararoop et al (2009), which also incorporates the effects of water in the coal matrix is used. The coal shrinkage and swelling model for multi-component systems can be written as:…”

A Mixed Element Method for the Desorption‐Diffusion‐Seepage Model of Gas Flow in Deformable Coalbed Methane Reservoirs

“…Comparing with conventional natural gas reservoirs, the effect of fracture systems deformation on permeability is significant in CBM reservoirs [2][3][4]. Meanwhile, the gas flow in fracture systems is driven not only by pressure field but also by gas concentration field [5,6], so we need to consider Darcy seepage and Fick diffusion simultaneously in multifield. As coalbed gas is released from CBM reservoirs, fracture system pressure reduces, resulting in gas diffusion in the coal matrix and gas desorption from coal matrix surface to fracture systems.…”

“…Based on the above understandings about coalbed gas flow mechanism, a series of conventional mathematical and numerical models [5,6,11,12] have been developed, obtaining some useful computational and simulation results. Young [11] presented a computer model for CBM reservoirs to determine key data and to describe the variability in CBM reservoir properties.…”

“…Unsal et al [12] proposed a numerical model for multiphase flow in CBM reservoirs using a fracture-only model. Thararoop et al [5,6] developed a compositional dual porosity, dual permeability CBM numerical model to describe the pressure and concentration dynamic behaviors. Nevertheless, the existing CBM numerical simulation methods are based on finite difference scheme and mainly focus on gas pressure and concentration, ignoring gas flow velocity.…”