Wetting Dynamics of Spontaneous Imbibition in Porous Media: From Pore Scale to Darcy Scale

Qin, Chaozhong; Wang, Xin; Hefny, Mahmoud; Zhao, Jianlin; Chen, Sidian; Guo, Bo

doi:10.1029/2021gl097269

Cited by 13 publications

(7 citation statements)

References 64 publications

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“…As such, their validity for viscoelastic fluids is questionable. In a recent work, Qin et al 28 have demonstrated that, for Newtonian fluids, the closed conduits in heterogeneous porous materials such as sandstone can affect the wetting dynamics of the displacing liquid. It can be argued that the situation becomes much more complicated for viscoelastic fluids because, for such fluids, the open conduits are regions of high elastic stresses, while the closed conduits are regions of low shear stress.…”

Section: Two-phase Imbibition Model For Viscoelastic Liquidsmentioning

confidence: 99%

Viscoelastic Effects on Spontaneous Imbibition in Unsaturated Porous Membranes of Complex Shapes

Gharagozlou,

Pourjafar-Chelikdani,

Jafari

et al. 2024

Langmuir

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Richards equation is a robust mathematical model for predicting spontaneous imbibition in unsaturated porous materials, whether granular or fibrous. The main restriction of this imbibition model is that it is valid only for Newtonian fluids. In the present work, we extend the classic Richards equation to viscoelastic fluids using a modified version of the single-phase Darcy's law reported in the literature for several polymer solutions. In two-dimensional flows, the viscoelastic Richards model obtained this way turns out to be in the form of a system of three highly nonlinear coupled partial differential equations for the moisture content and the velocity field. The model is numerically validated against published experimental data for a shear-thinning polymer solution imbibed in a tight sandstone core sample extracted from a typical oil reservoir. The viscoelastic Richards model is then used to investigate the effect of a fluid's elasticity on the quasi-stationary regime in a two-dimensional porous membrane of complex shape typically used in diagnostic kits. The obtained numerical results suggest that elasticity has a retarding effect on spontaneous imbibition in capillary-driven, paper-based kits. Based on this new imbibition model, it is predicted that viscoelasticity of the displacing liquid can extend the duration of the quasi-stationary regime on the test line of diagnostic kits. The conclusion is that, for extending the quasi-steady regime in capillary-driven kits, it might prove useful to enhance the degree of elasticity of the test fluids using appropriate rheology modifiers.

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Section: Two-phase Imbibition Model For Viscoelastic Liquidsmentioning

confidence: 99%

Viscoelastic Effects on Spontaneous Imbibition in Unsaturated Porous Membranes of Complex Shapes

Gharagozlou,

Pourjafar-Chelikdani,

Jafari

et al. 2024

Langmuir

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“…The volume of fracturing water injected into each well is typically more than 50,000 m 3 . However, only 5–50% of the injected fracturing water returns to the surface after the fracturing process due to leak-off and capillary imbibition from the fracture face into the shale matrix. − Recent experimental observations suggest that because shale formation exhibits ultra-low initial water saturation and high clay content, the imbibed water and clay swelling may block the gas transport pathway in the shale matrix (Figure ), thus preventing migration of shale gas to the fracture. − The impact of retained fracturing water on shale gas transport (gas diffusivity and permeability) has been evaluated in many published literature studies. Chen et al (2022) reported 57% reduction in diffusivity when Longmaxi organic-rich shale was exposed to water for 48 h. A similar blockage effect was also documented in many other organic-rich tight rocks dominated by nanopore systems. − The negative effect on matrix permeability is also observed to be a drastic reduction when exposed to water.…”

Section: Introductionmentioning

confidence: 99%

Heating-Induced Enhancement of Shale Gas Transport and Its Application for Improving Hydraulic Fracturing Performance

et al. 2022

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Enhancing the gas transport capacity of shale is essential to obtain economical gas production. Thermal stimulation has been theoretically and experimentally proven as a feasible technology for improving shale gas extraction. In this work, Longmaxi organic-rich shale samples were heated at 200−1000 °C for 240 h to investigate the feasibility of heating-induced generation of additional gas transport pathways and improvement of gas transport capacity (diffusivity and permeability) within the shale matrix. Results show that the mass loss of shale samples is basically unchanged after 200 °C, while a significant mass loss ranging from 3.5 to 14.4% can be observed in the heat treatment at 400−1000 °C. Decomposition (e.g., organic matter, calcite, and dolomite) and clay dehydration are the primary causes of shale mass loss. The organic matter in the shale remained unchanged after 200 °C heat treatment but greatly reduced, until almost disappeared, after 400 and 600 °C heat treatments, and the content of carbonate minerals dropped sharply, until almost disappeared, after 600−1000 °C heat treatment. Nitrogen adsorption experiments and in situ scanning electron microscopy observations show a significant improvement of pore volume and pore size after 400−600 °C heat treatment. However, the mineral melt and recrystallization after the heat treatment at 800 and 1000 °C can cause pore destruction and densification, resulting in pore volume decrease, indicating that the best heating temperature in Longmaxi shale samples is around 600 °C to enhance the pore volume and connectivity in the shale matrix. The methane adsorption decreased by 63.0%, the effective diffusion coefficient in the macropore increased by 263 times after 600 °C, and the permeability increased by 212.8 times at 5 MPa confining pressure. The newly formed transport pathways derived from 600 °C heat treatment may also improve shale matrix permeability at a high effective stress ranging from 30 to 65 MPa, which is a typical stress condition in the shale formations 2000−4500 m in depth. Based on the experimental results in this study, we proposed the heat treatment to improve hydraulic fracturing performance by mitigating fracturing-induced formation damage (e.g., water blockage, clay swelling, and secondary precipitation) within the fracture−matrix interface. In situ combustion of shale gas in hydraulic fractures may be a possible method to heat the shale formations and generate heating-induced transport pathways on the wall surfaces of hydraulic fractures.

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“…The network can be either extracted from pore space for real applications or generated artificially for mechanism study. In recent years, exciting developments have been made in algorithms for PNMs (Chen et al., 2021; Mehmani & Xu, 2022; Qin et al., 2022; Xie et al., 2017), yet, the efforts paid to network extraction from real pore space, which is the basis of pore network modeling for real applications, are still not enough. In the early studies of PNMs, regular networks (Chatzis & Dullien, 1977; Jerauld & Salter, 1990) were mostly adopted.…”

Section: Introductionmentioning

confidence: 99%

A Pore‐Throat Segmentation Method Based on Local Hydraulic Resistance Equivalence for Pore‐Network Modeling

Liu

Gong

Wang

et al. 2022

Water Resources Research

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The pore network is an approximate representation of the void space of porous materials, such as rocks and soil, via pores (corresponding to large cavities) and throats (narrow constrictions). During extraction of networks from real void space, ambiguous definitions or determinations of pores and throats may cause significant errors in the prediction of single/multi‐phase transport properties. Meanwhile, the pore‐throat segmentation needs to exclude non‐physical parameters as much as possible. In this work, we propose a pore‐throat segmentation method based on local hydraulic resistance equivalence between the real void space and the simplified pore‐throat geometry. Each pore‐throat interface is carefully determined at the position where the simplified tubes preserve the local hydraulic resistance of the real space best. This local segmentation method ensures equivalency between extracted pore network and real pore space without any empirical or non‐physical parameters. After validations of accuracy and reliability by benchmarks, this method is applied to real porous materials including spherical pack, sand pack, sandstone, limestone, and carbonate. The single/two‐phase transport properties predicted by the new method agree well with the experimental data and the direct simulation results. The proposed method improves the accuracy of pore network model (PNM) predictions significantly with a slight increase in computational cost. This local pore‐throat segmentation method may enhance the capability of PNM for more complicated applications.

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Wetting Dynamics of Spontaneous Imbibition in Porous Media: From Pore Scale to Darcy Scale

Cited by 13 publications

References 64 publications

Viscoelastic Effects on Spontaneous Imbibition in Unsaturated Porous Membranes of Complex Shapes

Viscoelastic Effects on Spontaneous Imbibition in Unsaturated Porous Membranes of Complex Shapes

Heating-Induced Enhancement of Shale Gas Transport and Its Application for Improving Hydraulic Fracturing Performance

A Pore‐Throat Segmentation Method Based on Local Hydraulic Resistance Equivalence for Pore‐Network Modeling

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