A Capillary Network Model for Coupled Gas and Water Flow in Engineered Barriers

1995 ◽  
Vol 412 ◽  
Author(s):  
M. D. Impy ◽  
P. Grindrod ◽  
K. J. Clark ◽  
H. Takase
Keyword(s):  
Network Model ◽  
Capillary Network ◽  
Low Permeability ◽  
Gas Migration ◽  
Capillary Bundle ◽  
Saturated Media ◽  
Engineered Barriers ◽  
Water Saturated ◽  
Preferential Pathways ◽  
Saturated Medium

AbstractA two-dimensional capillary network model for gas migration through a water-saturated medium is presented. The model is an extension of previously developed capillary bundle models, and provides a discrete alternative to classical continuum Darcy models. The need for such an alternative has become apparent from recent experimental results that suggest gas migrates through low permeability water-saturated media via a small number of preferential pathways.

A Capillary Network Model for Gas Migration in Low-Permeability Media

1997 ◽  
Vol 57 (3) ◽  
pp. 597-608 ◽  
Author(s):  
H. Takase ◽  
K. J. Worgan ◽  
M. D. Impey ◽  
P. Grindrod
Keyword(s):  
Network Model ◽  
Capillary Network ◽  
Low Permeability ◽  
Gas Migration

scholarly journals Development of a mathematical model for gas migration (two-phase flow) in natural and engineered barriers for radioactive waste disposal

2018 ◽  
Vol 482 (1) ◽  
pp. 115-148 ◽  
Author(s):  
E. E. Dagher ◽  
T. S. Nguyen ◽  
J. A. Infante Sedano
Keyword(s):  
Mathematical Model ◽  
Radioactive Waste ◽  
Expansive Soil ◽  
Low Permeability ◽  
Phase Flow ◽  
Gas Migration ◽  
Two Phase ◽  
Flow Through ◽  
Engineered Barriers

AbstractIn a deep geological repository (DGR) for the long-term containment of radioactive waste, gases could be generated through a number of processes. If gas production exceeds the containment capacity of the engineered barriers or host rock, these gases could migrate through these barriers and potentially expose people and the environment to radioactivity. Expansive soils, such as bentonite-based materials, are currently the preferred choice of seal materials. Understanding the long-term performance of these seals as barriers against gas migration is an important component in the design and long-term safety assessment of a DGR. This study proposes a hydro-mechanical linear poro-elastic visco-capillary mathematical model for advective-diffusive controlled two-phase flow through a low-permeability expansive soil. It is based on the theoretical framework of poromechanics, incorporates Darcy's Law for both the porewater and poregas, and a modified Bishop's effective stress principle. Using the finite element method (FEM), the model was used to numerically simulate 1D flow through a low-permeability expansive soil. The results were verified against experimental results found in the current literature. Parametric studies were performed to determine the influence on the flow behaviour. Based on the results, the mathematical model looks promising and will be improved to model flow through preferential pathways.

Gas migration through water-saturated bentonite–sand mixtures, COx argillite, and their interfaces

2016 ◽  
Vol 53 (1) ◽  
pp. 60-71 ◽  
Author(s):  
Jiang-Feng Liu ◽  
Yang Song ◽  
Frédéric Skoczylas ◽  
Jian Liu
Keyword(s):  
Gas Flow ◽  
Nuclear Waste Repository ◽  
Gas Migration ◽  
Initial State ◽  
Flow Rates ◽  
Sand Mixture ◽  
Migration Pathway ◽  
Order Of Magnitude ◽  
Water Saturated ◽  
Preferential Pathways

France’s deep-seated nuclear waste repository consists of a natural barrier located at a depth of 500 m in a Callovo-Oxfordian clayey formation. This repository has artificial barriers that include plugs of swelling clay (MX80 bentonite – sand mixtures) for sealing purposes. This paper focuses on the gas migration properties of water-saturated bentonite–sand mixtures and their interfaces with COx argillite. The main contribution of our study is the identification of a preferential gas migration pathway by measuring the downstream gas breakthrough pressures and gas flow rates. The water permeabilities of the bentonite–sand mixtures and their interfaces with COx argillite or COx argillite itself are the same order of magnitude (10−20–10−21 m2). Thus, water tightness can be obtained for these materials when they become completely saturated. The results obtained from the gas breakthrough tests suggest that both the COx argillite and its interface with the bentonite–sand mixture can act as preferential pathways for gas migration. The transport of the gas through the COx argillite or through its interface with the bentonite–sand mixture depends on the initial state of the COx argillite.

scholarly journals A Study of Compositions Relevant to Selective Water Isolation in Gas Wells

2021 ◽  
Author(s):  
Sudad H Al-Obaidi ◽  
Hofmann M ◽  
Smirnov VI ◽  
Khalaf FH ◽  
Hiba H Alwan
Keyword(s):  
Porous Media ◽  
High Selectivity ◽  
High Water ◽  
Saturated Porous Media ◽  
Hole Formation ◽  
Gas Wells ◽  
Bottom Hole ◽  
Formation Zone ◽  
Saturated Media ◽  
Water Saturated

A hydrophobic composition containing water repellents and highly volatile solvents is shown in this study to isolate water from the bottom hole formation zone of gas wells and reduce as much as possible the saturation of pore spaces with water. During injection, this composition shows selectivity and mostly penetrates water-saturated porous media. The study shows that the injection of such composition into porous media has a high water-insulating effect, reducing the water permeability of water-saturated porous media by 35 times with a degree of water isolation of 97%.Moreover, while injecting, it has selective action, mainly penetrating water-saturated media rather than gas saturated media. As a result of injecting 0.91 to 0.99 pore volumes (pv) of the composition, the Qwater/Qgas ratio reaches 5.22 to 5.26, indicating high selectivity.

Effect of Neutrophils Retention Time in Capillaries on Increase in Their Concentration in a Lattice Capillary Network Model

2007 ◽  
Author(s):  
Atsushi Shirai ◽  
Toshiyuki Hayase
Keyword(s):  
Immune System ◽  
Network Model ◽  
Host Defense ◽  
Retention Time ◽  
Systemic Circulation ◽  
Capillary Network ◽  
Know How ◽  
Pulmonary Capillary ◽  
And Behavior ◽  
Normal Lungs

Neutrophils are known as the most popular cells in leukocytes, and play important roles in immune system. They are retained in pulmonary capillary network even in normal lungs, causing higher concentration than in systemic circulation due to their low deformability [1]. The lungs can be a route for pathogenic substances to invade the host, since thickness of septa which separates blood and outer air is extremely thin. However, the highly concentrated neutrophils are thought to be effectively recruited to the sites of inflammation for the host defense. Therefore, it is essential to know how neutrophils flow in pulmonary capillary microvasculature for the understanding of their functions and behavior in immune system.

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