Modeling gas displacement kinetics in coal with Maxwell‐Stefan diffusion theory

Wei, Xiaorong; Wang, Geoff; Massarotto, P.; Rudolph, Victor; Golding, Suzanne D.

doi:10.1002/aic.11314

Cited by 16 publications

(11 citation statements)

References 36 publications

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“…Maxwell-Stefan diffusion theory [56] is superior for describing diffusion of mixed gases in coals compared with the constant Fick diffusivity model. So far many attempts have been made to model gases diffusion in coals and the results suggested that the diffusion coefficient is strongly dependent on gas species and concentration [11,28,62,65,68].…”

Section: Multicomponent Gas Counter-diffusion In Coal Matrixmentioning

confidence: 99%

“…sorption, gas flow, and play important roles for CBM recovery as summarized in Table 2. 2.3 Coupling processes in CBM recovery CBM recovery results from migration of gas in coal, simultaneously dealing with the several coupling processes, i.e. gas sorption, gas diffusion, gas flow and permeability change responded to adsorption/desorption, diffusion and gas flow [28,29], as illustrated in Fig. 4.…”

Section: Overall Process Of Gas Transport In Coalmentioning

confidence: 99%

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A review on transport of coal seam gas and its impact on coalbed methane recovery

Wang

Xiao-dong

Wei

et al. 2011

Front. Chem. Sci. Eng.

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This paper presents a summary review on mass transport of coal seam gas (CSG) in coal associated with the coalbed methane (CBM) and CO 2 geo-sequestration enhanced CBM (CO 2 -ECBM) recovery and current research advances in order to provide general knowledge and fundamental understanding of the CBM/ECBM processes for improved CBM recovery. It will discuss the major aspects of theory and technology for evaluation and development of CBM resources, including the gas storage and flow mechanism in CBM reservoirs in terms of their differences with conventional natural gas reservoirs, and their impact on CBM production behavior. The paper summarizes the evaluation procedure and methodologies used for CBM exploration and exploitation with some recommendations.

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Section: Multicomponent Gas Counter-diffusion In Coal Matrixmentioning

confidence: 99%

Section: Overall Process Of Gas Transport In Coalmentioning

confidence: 99%

A review on transport of coal seam gas and its impact on coalbed methane recovery

Wang

Xiao-dong

Wei

et al. 2011

Front. Chem. Sci. Eng.

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“…Because it cannot be measured directly, there exists uncertainty in the values of tortuosity of nanoporous materials. Values between 1.5 and 8 have been reported by Wei et al (2007) and Busch et al (2008). If the kerogen porosity (the first parenthesis term on the right-hand side of Eq.…”

Section: Pore-scale Considerations In Organic-rich Gas Shalementioning

confidence: 99%

Carbon Dioxide Storage Capacity of Organic-Rich Shales

et al. 2011

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This paper presents an experimental study on the ability of organic-rich-shale core samples to store carbon dioxide (CO 2). An apparatus has been built for precise measurements of gas pressure and volumes at constant temperature. A new analytical methodology is developed allowing interpretation of the pressure/volume data in terms of measurements of total porosity and Langmuir parameters of core plugs. The method considers pore-volume compressibility and sorption effects and allows small gas-leakage adjustments at high pressures. Total gas-storage capacity for pure CO 2 is measured at supercritical conditions as a function of pore pressure under constant reservoir-confining pressure. It is shown that, although widely known as an impermeable sedimentary rock with low porosity, organic shale has the ability to store significant amount of gas permanently because of trapping of the gas in an adsorbed state within its finely dispersed organic matter (i.e., kerogen). The latter is a nanoporous material with mainly micropores (< 2 nm) and mesopores (2-50 nm). Storage in organic-rich shale has added advantages because the organic matter acts as a molecular sieve, allowing CO 2-with linear molecular geometry-to reside in small pores that the other naturally occurring gases cannot access. In addition, the molecular-interaction energy between the organics and CO 2 molecules is different, which leads to enhanced adsorption of CO 2. Hence, affinity of shale to CO 2 is partly because of steric and thermodynamic effects similar to those of coals that are being considered for enhanced coalbed-methane recovery. Mass-transport paths and the mechanisms of gas uptake are unlike those of coals, however. Once at the fracture/matrix interface, the injected gas faces a geomechanically strong porous medium with a dual (organic/inorganic) pore system and, therefore, has choices of path for its flow and transport into the matrix: the gas molecules (1) dissolve into the organic material and diffuse through a nanopore network and (2) enter the inorganic material and flow through a network of irregularly shaped voids. Although gas could reach the organic pores deep in the shale formation following both paths, the application of the continua approximation requires that the gas-flow system be near or beyond the percolation threshold for a consistent theoretical framework. Here, using gas permeation experiments and history matching pressure-pulse decay, we show that a large portion of the injected gas reaches the organic pores through the inorganic matrix. This is consistent with scanning-electron-microscope (SEM) images that do not show connectivity of the organic material on scales larger than tens of microns. It indicates an in-series coupling of the dual continua in shale. The inorganic matrix permeability, therefore, is predicted to be less, typically on the order of 10 nd. More importantly, although transport in the inorganic matrix is viscous (Darcy) flow, transport in the organic pores is not due to flow but mainly to molecular transport...

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“…A dynamic multi-component transport (DMCT) model [22,23] was developed to deal with multi component gas counter-diffusionand flow in the coal matrix. Figure 6 shows the conceptual model.…”

Section: Research Backgroundmentioning

confidence: 99%

Study on coal microstructure for porosity levels assessment

Miedzińska¹,

Niezgoda²,

Małek³

et al. 2013

Bulletin of the Polish Academy of Sciences: Technical Sciences

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The problem of methane existence in coal beds has been known for many years. It was and still it is a danger to coalminers. The aim of the research, presented in the paper, is to show and assess the porosity structure (especially micro and nanoporosity) in accordance to the dimensions of carbon dioxide particle. The characteristic surface morphology of the sample and the disclosure of the carbon porous structure have been obtained using the scanning electron microscope (SEM). The presented study of the coal microstructure is a part of the coal demethanation method with the use of liquid CO2, that has been proposed by the Military University of Technology.

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Modeling gas displacement kinetics in coal with Maxwell‐Stefan diffusion theory

Cited by 16 publications

References 36 publications

A review on transport of coal seam gas and its impact on coalbed methane recovery

A review on transport of coal seam gas and its impact on coalbed methane recovery

Carbon Dioxide Storage Capacity of Organic-Rich Shales

Study on coal microstructure for porosity levels assessment

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