A Discussion of the Effect of Tortuosity on the Capillary Imbibition in Porous Media

Cai, Jingong; Yu, Bo

doi:10.1007/s11242-011-9767-0

Cited by 376 publications

(187 citation statements)

References 53 publications

(65 reference statements)

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“…However, some recent literature reported that the time exponent was not always 0.5. Cai and Yu (2011) introduced fractal to characterize the tortuosity of imbibition streamline, and theoretically found that the time exponent was related to tortuosity fractal dimension. Hu et al (2012) demonstrated that the time exponent can reflect the pore connectivity of the tight rock.…”

Section: Completely Counter-current Imbibitionmentioning

confidence: 99%

A critical review on fundamental mechanisms of spontaneous imbibition and the impact of boundary condition, fluid viscosity and wettability

Meng

Liu

Wang

2017

Adv. Geo-Energ. Res.

107

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Spontaneous imbibition (SI) is one of the primary mechanisms of oil production from matrix system in fractured reservoirs. The main driving force for SI is capillary pressure. Researches relating to SI are moving fast. In the past few years, amount of literature on the development of SI with respect to many variables, such as mechanism of imbibition, scaling of imbibition data and wettability of matrix blocks. In this review, we first introduced the fundamental physics mechanism of SI through capillary tube models and micromodels. Then both conventional and more novel experimental methods of measuring oil production are discussed thoughtfully. This is followed by reviewing the oil production performance under various boundary conditions and the characteristic length in scaling equations that have been used to account for different cores shape and boundary conditions. The effect of fluid viscosity on the rate of oil production and final oil recovery as well as the development of viscosity term in the scaling equation are reported. The commonly used methods to quantitatively evaluate the wettability of cores and the SI under mix-and oil-wet conditions are introduced. And last but not least, the methods and mechanism of wettability alteration for enhanced oil recovery in mix-or oil-wet fractured reservoirs are presented.Keywords: Spontaneous imbibition, fractured reservoirs, boundary condition, viscosity ratio, wettability.Citation: Meng, Q., Liu, H., Wang, J. A critical review on fundamental mechanisms of spontaneous imbibition and the impact of boundary condition, fluid viscosity and wettability.

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Section: Completely Counter-current Imbibitionmentioning

confidence: 99%

A critical review on fundamental mechanisms of spontaneous imbibition and the impact of boundary condition, fluid viscosity and wettability

Meng

Liu

Wang

2017

Adv. Geo-Energ. Res.

107

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“…To directly calculate n value, the above curve is sometimes described in logarithmic coordinates; at this point, the imbibition index n manifests as the slope of a straight line segment on the curve in logarithmic coordinates. On the theoretical SI mechanism, Cai and Yu (2011) defined n as imbibition time exponent. It is worth noting that the exponent n is analytically expressed as a function of tortuosity fractal dimension, and in the range of 1/6e1/2 in Cai and Yu's fractal model.…”

Section: Basic Representative Elementary Structurementioning

confidence: 99%

Spontaneous imbibition in asymmetric branch-like throat structures in unconventional reservoirs

Shen

et al. 2017

Journal of Natural Gas Science and Engineering

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a b s t r a c tUnconventional reservoirs, especially shale plays, have abundant micro-nano pores. Large volume water was injected into the reservoir during hydraulic fracturing. Fracturing fluid can displace gas in pore spaces spontaneously, called spontaneous imbibition (SI), which has significant effects on the gas production after hydraulic fracturing. Throat structure in matrix is one of the key factors to influence SI process. In this work, at first, complex pore space is simplified as a spatial self-similar branch-like structure composed of several asymmetric sub-throats. Then, within asymmetric branch structure, the imbibition process is calculated by a newly established mathematical model, and the influence of both pore structure and fluid characteristics, including contract angle, viscosity, surface tension, are discussed. Finally, some lab experiments, especially SI tests, are included on shale and sandstone core plugs to verify our model. Results show that the coherence in wettability between the reservoir and the fracturing fluid is important to enhance the microscopic replacement effect. Pore size also has effect influence on imbibition curve. In addition, both in models and experiments, imbibition index n is useful to describe imbibition properties of rocks. In unconventional rock samples like shale, n is less than 0.4, while highpermeability sandstone, n approach to 0.5. These conclusions are useful to investigate the mechanism of spontaneous imbibition and microscopic displacement in unconventional reservoirs.

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“…Specifically, pore-connectivity effects, and consequently, phase trapping, residual saturations, and hysteresis have been disregarded in the straight tube-bundle models. Tortuous flow path with variably shaped apertures or with variable lengths have successfully been derived and applied in the flow properties characterization using fractal based approach (Cai and Yu, 2011;Cai et al, 2014a;Liu et al, 2016b). Thus, application of simple physical theory to simulate a capillary curve in a complex, irregular and disordered pore space is a missing requirement.…”

Section: Capillary Pressure Curves From Pore-scale Modelingmentioning

confidence: 99%

Applications of digital core analysis and hydraulic flow units in petrophysical characterization

Chen

Zhou

2017

Adv. Geo-Energ. Res.

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Conventional petrophysical characterizations are often based on direct laboratory measurements. Although they provide accurate results, such measurements are time-consuming and limited by instrument and environment. What's more, in the georesource energy industry, availability and cuttings of core plugs are difficult. Because of these reasons, virtual digital core technology is of increasing interest due to its capability of characterizing rock samples without physical cores and experiments. Virtual digital core technology, also known as digital rock physics, is used to discover, understand and model relationships between material, fluid composition, rock microstructure and macro equivalent physical properties. Based on actual geological conditions, modern mathematical methods and imaging technology, the digital model of the core or porous media is created to carry out physical field numerical simulation. In this review, the methods for constructing digital porous media are introduced first, then the characterization of thin rock cross section and the capillary pressure curve using scanning electron microscope image under mixed wetting are presented. Finally, we summarize the hydraulic flow unit methods in petrophysical classification.Keywords: Digital core, porous media, petrophysical characterization, thin section, mercury injection capillary pressure.Citation: Chen, X., Zhou, Y. Applications of digital core analysis and hydraulic flow units in petrophysical characterization. Adv.

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A Discussion of the Effect of Tortuosity on the Capillary Imbibition in Porous Media

Cited by 376 publications

References 53 publications

A critical review on fundamental mechanisms of spontaneous imbibition and the impact of boundary condition, fluid viscosity and wettability

A critical review on fundamental mechanisms of spontaneous imbibition and the impact of boundary condition, fluid viscosity and wettability

Spontaneous imbibition in asymmetric branch-like throat structures in unconventional reservoirs

Applications of digital core analysis and hydraulic flow units in petrophysical characterization

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