A study on how to couple thermo-hydro-mechanical behaviour of unsaturated soils: Physical equations, numerical implementation and examples

Abed, Ayman; Sołowski, Wojciech Tomasz

doi:10.1016/j.compgeo.2017.07.021

Cited by 70 publications

(51 citation statements)

References 69 publications

(101 reference statements)

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“…For example, water is found as liquid and as vapour in the gas phase whereas besides the dry air in the pores, dissolved dry air can be found in the liquid phase. The detailed derivation of the balance equations in Thebes code can be found in [2,3]. For the purposes of this paper, only water and dry air mass balance equations are presented in the following sections.…”

Section: Mass Balancementioning

confidence: 99%

“…Assumptions related to thermal flow and salt transport are also needed if the tackled problem is non-isothermal and chemical effects to be studied. For a deeper look on the derivation and the adopted constitutive assumptions, the reader is referred to [2,3].…”

Section: Water Mass Balance Equationmentioning

confidence: 99%

“…The derivation of dry air mass balance equation follows from the sum of dry air mass in the geomaterial voids and the mass of dissolved dry air in the liquid water. The corresponding equation is written as [3]:…”

Section: Dry Air Mass Balance Equationmentioning

confidence: 99%

“…The coupled thermo-hydro-mechanical-chemical balance equations are discretised spatially using the finite element method [3]. This results in a set of first order differential equations of the form:…”

Section: Numerical Implementationmentioning

confidence: 99%

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Modelling of unsaturated gas flow by Thebes code: Validation tests

Abed

Sołowski

2020

E3S Web Conf.

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This paper presents the simulations replicating two well-documented benchmarks on coupled gas-liquid flow in unsaturated soil. The results serve as validation and verification of the formulation of the gas flow in unsaturated geomaterials in the newly developed THMC coupled FEM code Thebes. The paper first discusses the basis of the compositional method and the role of the dry air mass balance equation in the theoretical framework. The fundamental constitutive assumptions related to gas flow, as adopted in the Thebes code, are also discussed in details. Afterwards, the paper discusses simulation of a two-phase infiltration test in unsaturated sand, as well as a one dimensional drainage test. The numerical results of these two examples show that the code is able to capture the main features associated with the gas flow in unsaturated soil. The possible future improvements, both related to the theoretical framework and the numerical implementation, are discussed at the closure of the paper.

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Section: Mass Balancementioning

confidence: 99%

Section: Water Mass Balance Equationmentioning

confidence: 99%

Section: Dry Air Mass Balance Equationmentioning

confidence: 99%

Section: Numerical Implementationmentioning

confidence: 99%

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Modelling of unsaturated gas flow by Thebes code: Validation tests

Abed

Sołowski

2020

E3S Web Conf.

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“…CBM thermal recovery donates a multi-physical issue of coal, gas and heat [32,33]. Abed et al [34] described a thermo-hydro-mechanical (THM) framework that suitable for modeling the behavior of unsaturated soils and rock. Due to the CBM thermal recovery method of microwave heating, Gao et al [35] illustrated the interactions among temperature field, coalbed compaction, and methane transfer.…”

Section: Introductionmentioning

confidence: 99%

Mathematical Modeling and Simulation on the Stimulation Interactions in Coalbed Methane Thermal Recovery

Teng

Wang

et al. 2019

Processes

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Heat stimulation of coalbed methane (CBM) reservoirs has remarkable promotion to gas desorption that enhances gas recovery. However, coalbed deformation, methane delivery and heat transport interplay each other during the stimulation process. This paper experimentally validated the evolutions of gas sorption and coal permeability under variable temperature. Then, a completely coupled heat-gas-coal model was theoretically developed and applied to a computational simulation of CBM thermal recovery based on a finite element approach of COMSOL with MATLAB. Modeling and simulation results show that: Although different heat-gas-coal interactions have different effects on CBM recovery, thermal stimulation of coalbed can promote methane production effectively. However, CBM thermal recovery needs a forerunner heating time before the apparent enhancement of production. The modeling and simulation results may improve the current cognitions of CBM thermal recovery.Processes 2019, 7, 526 2 of 16 that the reservoir temperature increases 30 • C in twelve years to finally expand the methane production by 58% compared to the conventional method of direct recovery. Li et al.[12] established a mathematical model before demonstrating the complicated couplings among coalbed, methane and temperature. The model was then applied to a CBM thermal recovery of microwave heating. Research results show that thermal stimulation with microwave expands methane recovery more than 40% due to the deformation induced by gas sorption. Khoshnevis et al. [13] investigated the synergy type of gas production by injecting geothermal water. They established a three-dimension model to discuss the production potential of gas field and the influences of injection rate, reservoir permeability, saturation condition on the ultimate methane production. Lu [14] proposed a numerical simulation of heat injection into a three-dimensional temperature field by ANSYS to evidence the increasing production of CBM with temperature due to the easier desorption with higher temperature. Shahtalebi et al. [15] point out that the costs in coalbed methane thermal production limit the economic effectiveness. Only when the price of natural gas is comparatively higher and the demand for clean energy is stronger, the method of thermal production can become an economically attractive option.CBM thermal recovery benefits a lot from the enhanced gas adsorption behavior [16][17][18]. Sakurovs et al. [19] presented three sets of experimental sorption evolutions at variable temperature. The results show that the methane adsorption capacity has great dependency with coal temperature. The sorption of coal to methane at different temperature ranges may indicate different behaviors, and a traditional Langmuir equation cannot describe the different trends. For example, Guan et al. [20,21] estimated the adsorption isotherms at temperatures from 283 K to 343 K. They find that the adsorption capacity of CBM decreases linearly with increasing temperature at the range of 283 K to 323 K, and keeps...

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Propagation of Rayleigh waves in unsaturated porothermoelastic media

Liu

Zhou

Wang

et al. 2020

Num Anal Meth Geomechanics

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SummaryBased on the frame of elastic theory for unsaturated porous medium, considering the influence of thermal effect, the propagation characteristics of Rayleigh wave in unsaturated porous media are studied. Firstly, the thermoelastic wave equations for three‐phase porous media are established, in which the mass balance equations, generalized Darcy law, momentum balance equations, and generalized non‐Fourier heat conduction law are taken into account. Secondly, through theoretical derivation, the dispersion equation of Rayleigh wave for unsaturated porothermoelastic media is given by introducing the potential functions. Finally, the variations of the phase velocity of Rayleigh wave are analyzed with numerical examples. The results show that the thermal conductivity has little effect on the phase velocity of Rayleigh wave. The phase velocity of Rayleigh wave increase with increasing of the thermal expansion coefficient and media temperature.

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A study on how to couple thermo-hydro-mechanical behaviour of unsaturated soils: Physical equations, numerical implementation and examples

Cited by 70 publications

References 69 publications

Modelling of unsaturated gas flow by Thebes code: Validation tests

Modelling of unsaturated gas flow by Thebes code: Validation tests

Mathematical Modeling and Simulation on the Stimulation Interactions in Coalbed Methane Thermal Recovery

Propagation of Rayleigh waves in unsaturated porothermoelastic media

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