Effect of gravity on spontaneous imbibition of the wetting phase into gas-saturated tortuous fractured porous media: Analytical solution and diagnostic plot

Wang, Fuyong; Cheng, Hui

doi:10.1016/j.advwatres.2020.103657

Cited by 22 publications

(9 citation statements)

References 41 publications

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“…The surface fractal dimension can therefore be utilized to indicate the roughness of fracture surfaces; in this model, the time exponent was found to be related to the surface fractal dimension. Targeting air-saturated fractured porous media, Wang and Cheng proposed a cumulative imbibition weight model with and without gravity based on the tortuous plate fracture model with the fractal theory. This new model attained a better performance in predicting the imbibition height over time in a fracture compared with the LW equation.…”

Section: Modifications and Extensions Of The Lw Equationmentioning

confidence: 99%

Lucas–Washburn Equation-Based Modeling of Capillary-Driven Flow in Porous Systems

et al. 2021

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Fluid flow in porous systems driven by capillary pressure is one of the most ubiquitous phenomena in nature and industry, including petroleum and hydraulic engineering as well as material and life sciences. The classical Lucas–Washburn (LW) equation and its modified forms were developed and have been applied extensively to elucidate the fundamental mechanisms underlying the basic statics and dynamics of the capillary-driven flow in porous systems. The LW equation assumes that fluids are incompressible Newton ones and that capillary channels all have the same radii. This kind of hypothesis is not true for many natural situations, however, where porous systems comprise complicated pore and capillary channel structures at microscales. The LW equation therefore often leads to inaccurate capillary imbibition predictions in such situations. Numerous studies have been conducted in recent years to develop and assess the modifications and extensions of the LW equation in various porous systems. Significant progresses in computational techniques have also been attained to further improve our understanding of imbibition dynamics. A state-of-the-art review is therefore needed to summarize the recent significant models and numerical simulation techniques as well as to discuss key ongoing research topics arising from various new engineering practices. The theoretical basis of the LW equation is first introduced in this review and recent progress in mathematical models is then summarized to demonstrate the modifications and extensions of this equation to various microchannels and porous media. These include capillary tubes with nonuniform and noncircular cross sections, discrete fractures, and capillary tubes that are not straight as well as heterogeneous porous media. Numerical studies on the LW equation are also reviewed, and comments on future works and research directions for LW-based capillary-driven flows in porous systems are listed.

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Section: Modifications and Extensions Of The Lw Equationmentioning

confidence: 99%

Lucas–Washburn Equation-Based Modeling of Capillary-Driven Flow in Porous Systems

et al. 2021

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“…The number and aperture of curved capillary tube bundles conform to the fractal scaling law. Based on fractal theory, − the scale of the imbibition models is upgraded.…”

Section: Imbibition Model Of Fractal Porous Mediamentioning

confidence: 99%

Mathematical Model and Application of Spontaneous and Forced Imbibition in Shale Porous Media-Considered Forced Pressure and Osmosis

Wang

et al. 2022

Energy Fuels

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The energized hydraulic fracturing technology of “energizing, hydraulic fracturing, shut-in, and flowback” has achieved good development results in some shale oil fields. The mechanisms of forced imbibition (FI) under forced pressure (the difference between hydraulic fluid pressure and original pore pressure) need to be further studied; especially, the difference and boundary of various mechanisms in forced soaking are still unclear. The wettability of pores is different, the reservoir shows strong mixed wettability, and the permeability of clay mineral pores has osmotic pressure. This paper analyzes the imbibition forces in distinct types of pores, and the dynamic models of spontaneous imbibition (SI) and FI in a single capillary tube are established. Based on the fractal theory and capillary bundle model, the mathematical models of SI and FI at the core scale are established, and semi-analytical solution models considering different forces are proposed, especially considering forced pressure and osmosis. In addition, the above mathematical models are fitted and verified by imbibition experiments and NMR, which ensured the accuracy and validity of the mathematical models. In this paper, the sensitivity analysis of different factors to oil displacement rate and oil recovery by imbibition is quantitatively evaluated. The research shows that the imbibition rate of FI is faster than that of SI, and the ultimate oil recovery is also higher. Smaller pores mainly control the imbibition rate, which increases with oil–water interfacial tension and forced pressure. However, the imbibition rate decreases with increasing water-phase viscosity and fractal dimension.

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“…In eq , L t and L s denote the actual length and straight length of liquid in the capillary, shown in Figure . According to the definition of tortuosity (actual length versus straight length), the relation between velocities along curved and straight pathways is expressed as where τ is the tortuosity of the capillary in the shale sample and v t and v s are the velocities in the actual capillary and straight capillary (nm/s).…”

Section: Model Of Shale Spontaneous Imbibitionmentioning

confidence: 99%

Novel Analytical Model of Shale Spontaneous Imbibition Considering the Hydration Effect

Ding

Liu

et al. 2021

Energy Fuels

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Shale gas has enormous potential and has become a hotspot in recent decades. To exploit shale gas, a variety of working fluids (drilling fluid, fracturing fluid, etc.) have to be applied in drilling and well-completion engineering. When fluid contacts with shale, spontaneous imbibition occurs, affecting wellbore stability, fracturing fluid loss, and shale gas production. In the past few years, numerous researchers conducted studies on shale spontaneous imbibition, yet the vast majority of their works are derived from conventional method based on sandstone and carbonate. One of the characteristics of shale is strong hydration, which has been widely reported. During the interaction between liquid and shale, spontaneous imbibition is accompanied by hydration. Shale hydration mainly involves two aspects, i.e., osmotic pressure and hydration structural damage. Now there is still no research on studying the hydration effect during spontaneous imbibition, and how hydration affects spontaneous imbibition is still not fully understood. Therefore, in this paper, considering osmotic pressure and hydration structural damage, spontaneous imbibition in shale formation has been investigated. Besides, according to the Hagen−Poiseuille law, a novel analytical model has been established by coupling imbibition and hydration. In comparison to experimental data of spontaneous imbibition, practicability of this spontaneous imbibition model has been verified. On the basis of this new model and spontaneous imbibition test, influences of salinity and hydration on shale spontaneous imbibition have been systematically discussed. Results indicate that salinity reduces spontaneous imbibition by lowering the driving force of imbibition and restricting hydration damage. Hydration structural damage is its major influencing mechanism for shale spontaneous imbibition. In the shale exploitation, this model can offer guidance for evaluating fracturing fluid loss and hydration damage, which are practical for drilling and hydraulic fracturing design. Besides, the outcome of this paper is beneficial for improving our understanding on spontaneous imbibition in shale formation.

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Effect of gravity on spontaneous imbibition of the wetting phase into gas-saturated tortuous fractured porous media: Analytical solution and diagnostic plot

Cited by 22 publications

References 41 publications

Lucas–Washburn Equation-Based Modeling of Capillary-Driven Flow in Porous Systems

Lucas–Washburn Equation-Based Modeling of Capillary-Driven Flow in Porous Systems

Mathematical Model and Application of Spontaneous and Forced Imbibition in Shale Porous Media-Considered Forced Pressure and Osmosis

Novel Analytical Model of Shale Spontaneous Imbibition Considering the Hydration Effect

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