Investigation on gas migration behaviours in saturated compacted bentonite under rigid boundary conditions

Cui, Lian; Masum, Shakil; Ye, Weimin; Thomas, Hywel Rhys

doi:10.1007/s11440-021-01424-1

Cited by 11 publications

(9 citation statements)

References 44 publications

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“…Based on the principle of mass conservation, the mass balance equation for a free gas in porous matrices can be expressed as (Chen et al, 2020b(Chen et al, , 2021Cui et al, 2022): where…”

Section: Free Gas Diffusion In Coal Matricesmentioning

confidence: 99%

Three-dimensional cleat scale modelling of gas transport processes in deformable fractured coal reservoirs

Chen¹,

Masum²,

Thomas³

2023

Gas Science and Engineering

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“…Based on the principle of mass conservation, the mass balance equation for a free gas in porous matrices can be expressed as (Chen et al, 2020b(Chen et al, , 2021Cui et al, 2022): where…”

Section: Free Gas Diffusion In Coal Matricesmentioning

confidence: 99%

Three-dimensional cleat scale modelling of gas transport processes in deformable fractured coal reservoirs

Chen¹,

Masum²,

Thomas³

2023

Gas Science and Engineering

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“…Meanwhile, researches con rmed that for the gas migrations in the porous media materials with an extremely low permeability, as the gas injection pressure increases, gas diffusion, viscous-capillary ow or two-phase ow, dilatancy controlled gas ow and gas ow along the macro-fractures, etc., can be observed successively (Marschall et al 2005;Ye et al 2014). Unfortunately, for gas transport in compacted bentonites, previous work mainly focused on the investigations related to gas breakthrough properties, rarely involving gas diffusion (Cui et al 2022;Cui et al 2020).…”

Section: Introductionmentioning

confidence: 99%

Gas diffusion property of compacted GMZ bentonite with consideration of saturation and gas pressure

Ye,

Ji,

et al. 2024

Preprint

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During the long-term operation of a deep geological repository, hydrogen, methane and carbon dioxide, etc. could be generated and accumulated in bentonite around canisters, threatening integrity and safety of engineering barrier systems. In this work, self-designed test apparatuses were developed. Gas diffusion tests were conducted on GMZ bentonite specimens under both rigid and flexible boundary conditions with consideration of initial saturations and gas pressures. After experienced the gas diffusion tests, the specimens were cut and submitted for the mercury intrusion porosimetry (MIP) tests. Results revealed that gas diffusion coefficient was obviously influenced by the initial saturations and gas pressures. As gas pressure increased from 1 to 4 MPa, a decrease of 55.3% ~ 58.8% and 17.7% ~ 73.4% in the diffusion coefficient were recorded for the specimens tested under rigid and flexible boundary, respectively. Compared to the rigid boundary conditions, the effective pore volume for gas molecule diffusion was further compressed under flexible boundary, resulting in a relatively poor pore connectivity and a lower gas diffusion coefficient. Meanwhile, the diffusion coefficient decreased with increasing initial saturations for the flexible boundary specimens, while an opposite trend was recorded for the rigid boundary ones. Explanations to this observation could be that under the rigid boundary conditions, specimens with higher initial saturations have larger diameter macro-pores, facilitating the gas diffusion.

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“…In recent studies, Cui et al [6] conducted a series of gas migration and breakthrough experiments on GMZ bentonites and analysed the results by employing a novel diffusion and solubility-controlled (DSC) flow concept [4]. The concept was developed and implemented under a coupled reactive gas transport model [25,34].…”

Section: Introductionmentioning

confidence: 99%

“…The concept was developed and implemented under a coupled reactive gas transport model [25,34]. The aim of the study [4] was to investigate the extent to which diffusion and solubility driven flow could explain gas migration behaviours in saturated, rigidly confined bentonites. From the detailed analysis, it was found that DSC can be used to describe gas flow and breakthrough behaviour in GMZ bentonites satisfactorily.…”

Section: Introductionmentioning

confidence: 99%

“…Helium gas was injected in water-saturated specimens using the residual capillary pressure (RCP) method. In this paper, the experimental results are analysed using the diffusion and solubility-controlled flow concept proposed in Cui et al [4]. The aim is to test and assess validity of the concept for describing the observed gas transport phenomena at higher temperatures.…”

Section: Introductionmentioning

confidence: 99%

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Numerical investigation of gas migration behaviour in saturated bentonite with consideration of temperature

Cui,

Masum,

et al. 2024

Acta Geotech.

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Gas migration behaviour in saturated, compacted bentonite, especially under rigid-boundary conditions, is controversial. Gas breakthrough phenomena, observed under higher pressure gradient conditions in laboratory experiments, are described in literatures by adopting visco-capillary or dilatancy-controlled flow concept. Since, under rigid-boundary conditions, volumetric expansion is restricted and/or water dissipation is not detected, these concepts cannot be implemented satisfactorily. Instead, a diffusion and solubility-controlled (DSC) flow concept was previously found to be adequate for describing the behaviours at lower temperatures (20 °C). The DSC concept describes gas breakthrough as a function of gas solubility. Breakthrough occurs when concentration of dissolved gas reaches or surpasses the solubility limit in the entire specimen. In this work, the DSC flow concept is applied to validate gas migration and breakthrough experiments conducted at higher temperatures, e.g. 40 and 60 °C. Good agreements are observed between the experimental and predicted results, suggesting that the DSC flow concept can be applied to describe gas migration behaviour satisfactorily in rigidly confined saturated bentonites (under constant volume conditions) for various temperature regimes. Results also show that helium dissolution and diffusion processes in saturated bentonite are sensitive to test temperature and pressure conditions. The processes become more stable with increasing gas injection pressure and ambient temperature.

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Investigation on gas migration behaviours in saturated compacted bentonite under rigid boundary conditions

Cited by 11 publications

References 44 publications

Three-dimensional cleat scale modelling of gas transport processes in deformable fractured coal reservoirs

Three-dimensional cleat scale modelling of gas transport processes in deformable fractured coal reservoirs

Gas diffusion property of compacted GMZ bentonite with consideration of saturation and gas pressure

Numerical investigation of gas migration behaviour in saturated bentonite with consideration of temperature

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