The impact of diffusion type on multiscale discrete fracture model numerical simulation for shale gas

Mi, Lidong; Jiang, Hanqiao; Li, Junjian

doi:10.1016/j.jngse.2014.06.013

Cited by 78 publications

(22 citation statements)

References 9 publications

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“…Klinkenberg firstly figured out the slippage with a modified equation and the similar method was used in the following researches of shale gas. [16][17][18][19] Thereafter, when 0.1 < Kn < 10, another mechanism of surface diffusion simultaneously occurs with the gas slippage. At this regime, the complex transport behavior is identified as transition flow.…”

Section: Introductionmentioning

confidence: 99%

Channel-width dependent pressure-driven flow characteristics of shale gas in nanopores

Chen

Fan

et al. 2017

AIP Advances

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Understanding the flow characteristics of shale gas especially in nanopores is extremely important for the exploitation. Here, we perform molecular dynamics (MD) simulations to investigate the hydrodynamics of methane in nanometre-sized slit pores. Using equilibrium molecular dynamics (EMD), the static properties including density distribution and self-diffusion coefficient of the confined methane are firstly analyzed. For a 6 nm slit pore, it is found that methane molecules in the adsorbed layer diffuse more slowly than those in the bulk. Using nonequilibrium molecular dynamics (NEMD), the pressure-driven flow behavior of methane in nanopores is investigated. The results show that velocity profiles manifest an obvious dependence on the pore width and they translate from parabolic flow to plug flow when the width is decreased. In relatively large pores (6 – 10 nm), the parabolic flow can be described by the Navier-Stokes (NS) equation with appropriate boundary conditions because of its slip flow characteristic. Based on this equation, corresponding parameters such as viscosity and slip length are determined. Whereas, in small pores (∼ 2 nm), the velocity profile in the center exhibits a uniform tendency (plug flow) and that near the wall displays a linear increase due to the enhanced mechanism of surface diffusion. Furthermore, the profile is analyzed and fitted by a piecewise function. Under this condition, surface diffusion is found to be the root of this anomalous flow characteristic, which can be negligible in large pores. The essential tendency of our simulation results may be significant for revealing flow mechanisms at nanoscale and estimating the production accurately.

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Section: Introductionmentioning

confidence: 99%

Channel-width dependent pressure-driven flow characteristics of shale gas in nanopores

Chen

Fan

et al. 2017

AIP Advances

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“…The jump model assumes that the adsorbed gas molecules jump from one adsorption site to the adjacent adsorption site on the pore surface, which is considered to be suitable for the research on the surface diffusion of the adsorbed gas in shale nanopores [37]. Meanwhile, when the molecular mean free path is obviously larger than the pore diameter, the gas-wall collision dominates, and the collision between gas molecules is secondary, which is characterized by Knudsen diffusion [9,38,39].…”

Section: Flow Mechanisms In Gas-shale Matrixmentioning

confidence: 99%

“…(5) and (6) into Eq. (8) as: (9) Literature survey shows that there are several main upscaling methods of flow models from microscopic to macroscopic scale, i.e. :…”

Section: Variations Of Viscous Flow and Diffusion With Kn (Dimensionlmentioning

confidence: 99%

Mechanism, Model, and Upscaling of the Gas Flow in Shale Matrix: Revisit

Hu¹,

Ya-Xiong²,

Li³

2022

Emerging Technologies in Hydraulic Fracturing and Gas Flow Modelling

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Shale gas accounts for an increasing proportion in the world's oil and gas supply, with the properties of low carbon, clean production, and huge potential for the compensation for the gradually depleted conventional resources. Due to the ubiquitous nanopores in shale matrix, the nanoscale gas flow becomes one of the most vital themes that are directly related to the formulation of shale gas development schemes, including the optimization of hydraulic fracturing, horizontal well spacing, etc. With regard to the gas flow in shale matrix, no commonly accepted consensus has been reached about the flow mechanisms to be considered, the coupled flow model in nanopores, and the upscaling method for its macroscopic form. In this chapter, the propositions of wall-associated diffusion, a physically sound flow mechanism scheme, a new coupled flow model in nanopores, the upscaling form of the proposed model, and the translation of lab-scale results into field-scale ones aim to solve the aforementioned issues. It is expected that this work will contribute to a deeper understanding of the intrinsic relationship among various flow mechanisms and the extension of the flow model to full flow regimes and to upscaling shale matrix, thus establishing a unified model for better guiding shale gas development.

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“…Refracturing is used to enhance production in a poorly fractured well [16]. The stimulation mechanism of refracturing lies in re-orientating fractures, avoiding decrease in permeability caused by proppant failures, re-orientating stress, opening the primary fracture, extending the primary fracture net, rinsing the fracture surfaces, refilling proppant, generating new fractures and obtaining a new effective fracture system.…”

Section: Refracturingmentioning

confidence: 99%

The Key and the Countermeasures Research of Shale Gas Fracturing Technology

Tang¹,

Wang²,

Zeng³

et al. 2015

TOPEJ

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Shale gas resources are abundantly distributed with low porosity and permeability. Horizontal well and fracturing are prior considerations. Fracturing is a widely-used technology to enhance gas production. In this paper, the author (a) investigated the present stimulation of Barnett and Haynesvile gas fields ( Fig. 1) in America, Sichuan basin (Fig. 2) in China and Cooper basin (Fig. 3) in Australia; (b) compared different characteristics and limitations of multi-stage fracturing, water-fracturing, simultaneous fracturing, net fracturing, refracturing and hydraulic jet fracturing; (c) analyzed the critical point of the shale fracturing; (d) offered solutions to the fracturing fluid manufacture, selection and improvement of the fracturing fluids, fractures extension, equipments, fracturing effect evaluation and reservoir protection. It has a farreaching significance to improve fracturing and stimulation of shale gas reservoirs, in view of the high risk, low success ratio and poor stimulation effect the shale gas exploration would face.

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The impact of diffusion type on multiscale discrete fracture model numerical simulation for shale gas

Cited by 78 publications

References 9 publications

Channel-width dependent pressure-driven flow characteristics of shale gas in nanopores

Channel-width dependent pressure-driven flow characteristics of shale gas in nanopores

Mechanism, Model, and Upscaling of the Gas Flow in Shale Matrix: Revisit

The Key and the Countermeasures Research of Shale Gas Fracturing Technology

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