Apparent permeability model for gas transport in shale reservoirs with nano-scale porous media

Wang, Shan; Shi, Juntai; Wang, Ke; Sun, Zheng; Miao, Yuqing; Hou, Chenhong

doi:10.1016/j.jngse.2018.05.026

Cited by 53 publications

(25 citation statements)

References 31 publications

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“…As analyzed in the aforementioned context, there are some differences in gas transport capacity for nanopores with different pore shapes. However, to date, nearly all of the production prediction models or related commercial software for shale gas recovery are based on a frequently utilized assumption; i.e., nanopore cross-sections in shale matrix are circles. − In order to enhance the rationality and accuracy of current production prediction models, it is necessary to take the effect of pore shapes on gas transport capacity into account, which directly affects gas production performance. In this section, the error caused by assuming nanopores with elliptical nanopores as circular nanopores will be quantified.…”

Section: Discussion About the Frequently Utilized Assumption In Shale...mentioning

confidence: 99%

Effect of Pore Shape on Nanoconfined Gas Flow Behavior: Implication for Characterizing Permeability of Realistic Shale Matrix

Shi

Sun

et al. 2019

Ind. Eng. Chem. Res.

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Good knowledge of nanoconfined gas flow behavior will significantly contribute to advance ultimate gas recovery from shale gas reservoirs. However, up to now, it has still been extremely challenging to have a clear understanding of the key issue. In particular, little attention is drawn to the effect of pore geometry on nanoconfined gas flow behavior. By means of developed experimental technology, realistic images reflecting pore characteristics can be obtained, which demonstrate that various pore shapes are exhibited in the shale matrix. To my knowledge, current related research is focused on gas transport through several conventional pore shapes, including circle, rectangle, and slit. As a result, the urgent issue, i.e., research on gas flow behavior through unconventional pore shapes, is highlighted. In this work, a model for gas transport through elliptical nanopores is established, which possesses an excellent varying-shape nature with changing aspect ratio (AR) and therefore covers lots of pore shapes and shares great application value. Both effects of gas slipperiness and surface diffusion are incorporated in this model. Moreover, the Langmuir isotherm is utilized to quantify the thickness of the adsorption layer of methane. When AR is equal to 1 and an infinite number, the proposed model can achieve excellent agreement compared with gas transport data through circular and slit-like nanopores. Results show that (a) the gas transport capacity will decrease with increasing AR value at a specific pressure point; (b) contribution of surface diffusion will become more prominent with higher AR value; (c) under different gas adsorption/desorption characteristics, there is no difference in gas transport capacity through nanopores with different ARs at high pressure and relatively large difference at low-pressure atmosphere; (d) current production prediction models or commercial software require consideration of the effect of various pore shapes to enhance application accuracy. In sum, the findings of this study can help in better understanding the methane flow feature through nanopores with various cross-sections, which further serve as the necessary theoretical attempt with regard to accurate characterization for flow capacity of a realistic shale matrix.

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Section: Discussion About the Frequently Utilized Assumption In Shale...mentioning

confidence: 99%

Effect of Pore Shape on Nanoconfined Gas Flow Behavior: Implication for Characterizing Permeability of Realistic Shale Matrix

Shi

Sun

et al. 2019

Ind. Eng. Chem. Res.

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“…32 • Organic and inorganic pores are arranged in parallel without transport from each other. [33][34][35] • Fluid transports in nanopores with a slip boundary condition and negligible capillary pressure.…”

Section: Conceptual Modelmentioning

confidence: 99%

Semianalytical method of two‐phase liquid transport in shale reservoirs and its application in fracture characterization

Zhang

Emami-Meybodi

2021

AIChE Journal

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This study presents a new semi-analytical method to simulate the two-phase liquid transport in hydraulic fractures (HF) and matrix system, which can be applied to characterize HF attributes and dynamics using the flowback data from hydraulically fractured shale oil wells. The proposed approach includes a fracture model for HF properties calculation and a matrix model capable of considering multiple liquid transport mechanisms in shale nanopores. The proposed method is first validated with the numerical simulation then applied to a field example in Eagle Ford shale. The numerical validation confirms that our method can accurately characterize fracture attributes and closure dynamics by closely estimating the initial fracture permeability, pore-volume, compressibility, and permeability modulus. Furthermore, the analysis results from numerical simulation and a field example both indicate a clear flow enhancement and deficit for oil and water transport, respectively, due to the slippage effect and variation of fluid properties inside nanopores.

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“…Li et al believed that it is debatable to superimpose the Knudsen diffusion and slip flow, or to superimpose the slip flow and surface diffusion, or to superimpose these three transport mechanisms in flow models. Since the shale gas mass transport mechanism was introduced from the theory of rarefied gas dynamics, the aerodynamic researcher also thought that, from the point of view of rarefied gas, slip flow was essentially the same as Knudsen diffusion, which was determined by the Boltzmann equation and gas-solid interaction, but the coefficients were different under different K n [37,38]. After that, Cai et al proposed a very interesting apparent permeability model by accounting for three major fluid flow mechanisms in shale stratum, which is modeled as a 3D fractal media.…”

Section: Model Formulamentioning

confidence: 99%

A Review of Gas Flow and Its Mathematical Models in Shale Gas Reservoirs

et al. 2020

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The application of horizontal wells with multistage hydraulic fracturing technologies has made the development of shale gas reservoirs become a worldwide economical hotspot in recent years. The gas transport mechanisms in shale gas reservoirs are complicated, due to the multiple types of pores with complex pore structure and special process of gas accumulation and transport. Although there have been many attempts to come up with a suitable and practical mathematical model to characterize the shale gas flow process, no unified model has yet been accepted by academia. In this paper, a comprehensive literature review on the mathematical models developed in recent years for describing gas flow in shale gas reservoirs is summarized. Five models incorporating different transport mechanisms are reviewed, including gas viscous flow in natural fractures or macropores, gas ad-desorption on shale organic, gas slippage, diffusion (Knudsen diffusion, Fick diffusion, and surface diffusion), stress dependence, real gas effect, and adsorption layer effect in the nanoshale matrix system, which is quite different from conventional gas reservoir. This review is very helpful to understand the complex gas flow behaviors in shale gas reservoirs and guide the efficient development of shale gas. In addition to the model description, we depicted the type curves of fractured horizontal well with different seepage models. From the review, it can be found that there is some misunderstanding about the essence of Knudsen/Fick diffusion and slippage, which makes different scholars adopt different weighting methods to consider them. Besides, the contribution of each mechanism on the transport mechanisms is still controversial, which needs further in-depth study in the future.

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Apparent permeability model for gas transport in shale reservoirs with nano-scale porous media

Cited by 53 publications

References 31 publications

Effect of Pore Shape on Nanoconfined Gas Flow Behavior: Implication for Characterizing Permeability of Realistic Shale Matrix

Effect of Pore Shape on Nanoconfined Gas Flow Behavior: Implication for Characterizing Permeability of Realistic Shale Matrix

Semianalytical method of two‐phase liquid transport in shale reservoirs and its application in fracture characterization

A Review of Gas Flow and Its Mathematical Models in Shale Gas Reservoirs

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