An Integrative Model To Simulate Gas Transport and Production Coupled With Gas Adsorption, Non-Darcy Flow, Surface Diffusion, and Stress Dependence in Organic-Shale Reservoirs

Wang, Jing; Luo, Haishan; Liu, Huiqing; Cao, Fei; Li, Zhitao; Sepehrnoori, Kamy

doi:10.2118/174996-pa

Cited by 62 publications

(27 citation statements)

References 29 publications

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“…Experimental results indicate that effective conductivity of both propped and unpropped fractures decreases with the decrease of effective stress [34]. According to the experimental results of Zhang et al [35], the relationship between the effective permeability and gas pressure can be written as:…”

Section: Gas Flow In Hydraulic Fracturementioning

confidence: 98%

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Effect of Permeability Anisotropy on the Production of Multi-Scale Shale Gas Reservoirs

Huang

Tao

et al. 2017

Energies

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Shales or mudstones are fine grained and layered reservoirs, which leads to strong shale permeability anisotropy. Shale has a wide pore-size distribution, and pores with different diameters contribute differently to the apparent permeability of shales. Therefore, understanding the anisotropy of multiscale shale gas reservoirs is an important aspect to model and evaluate gas production from shales. In this paper, a novel model of permeability anisotropy for shale gas reservoirs is presented to calculate the permeability in an arbitrary direction in three dimensional space. A numerical model which is valid for the entire Knudsen's range (continuum flow, slip flow, transition flow and free molecular flow) in shale gas reservoirs was developed, and the effect of gas-water flow and the simulation of hydraulic fracturing cracks were taken into consideration as well. The simulation result of the developed model was validated with field data. Effects of critical factors such as permeability anisotropy, relative permeability curves with different nanopore radii and initial water saturation in formation on the gas production rate of multi-stage fractured horizontal well were discussed. Besides, flow regimes of gas flow in shales were classified by Knudsen number, and the effect of various flow regimes on both apparent permeability of shales and then the gas production has been analyzed thoroughly.

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Section: Gas Flow In Hydraulic Fracturementioning

confidence: 98%

“…By applying the theory of equivalent fracture conductivity, the permeability of hydraulic fracture considering the stress-dependence effect can be calculated by [34]:…”

Section: Gas Flow In Hydraulic Fracturementioning

confidence: 99%

Effect of Permeability Anisotropy on the Production of Multi-Scale Shale Gas Reservoirs

Huang

Tao

et al. 2017

Energies

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“…In its experimental test, helium and methane were used to measure shale permeability, and the basic input parameters of model verification were shown in Table 1. Since gas viscosity is a function of pressure, the widely used formula is adopted to calculate, namely [47][48][49][50] (47) where γ g is gas molar weight, kg/mol. Since shale has no adsorption effect on helium gas, the effect of surface diffusion on apparent permeability is not considered when calculating the apparent permeability of helium gas.…”

Section: Model Validationmentioning

confidence: 99%

Multiscale Apparent Permeability Model of Shale Nanopores Based on Fractal Theory

Wang

Zhao

et al. 2019

Energies

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Based on fractal geometry theory, the Hagen–Poiseuille law, and the Langmuir adsorption law, this paper established a mathematical model of gas flow in nano-pores of shale, and deduced a new shale apparent permeability model. This model considers such flow mechanisms as pore size distribution, tortuosity, slippage effect, Knudsen diffusion, and surface extension of shale matrix. This model is closely related to the pore structure and size parameters of shale, and can better reflect the distribution characteristics of nano-pores in shale. The correctness of the model is verified by comparison with the classical experimental data. Finally, the influences of pressure, temperature, integral shape dimension of pore surface and tortuous fractal dimension on apparent permeability, slip flow, Knudsen diffusion and surface diffusion of shale gas transport mechanism on shale gas transport capacity are analyzed, and gas transport behaviors and rules in multi-scale shale pores are revealed. The proposed model is conducive to a more profound and clear understanding of the flow mechanism of shale gas nanopores.

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“…By applying the theory of equivalent fracture conductivity, the effective permeability of hydraulic fracture which considers the stress‐dependence effect can be calculated by:

K_{normaleH} = \frac{K_{normalH} \cdot w_{normalH}}{Δ x_{normalH}} = \frac{K_{normalHi} \cdot w_{normalH}}{Δ x_{normalH}} \cdot e^{- α_{normals} (p_{normalgi} - p_{normalg})} .

…”

Section: Simulation Of Shale Gas Reservoirmentioning

confidence: 99%

“…By applying the theory of equivalent fracture conductivity, the effective permeability of hydraulic fracture which considers the stress-dependence effect can be calculated by 48 :…”

Section: Gas Flow In Hydraulic Fracturesmentioning

confidence: 99%

A novel numerical model of gas transport in multiscale shale gas reservoirs with considering surface diffusion and Langmuir slip conditions

Huang

Cao

Yuan

et al. 2019

Energy Science & Engineering

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Multiflow mechanisms coexist in shale gas reservoirs (SGRs) due to the abundant nanopores and the organic matter as a medium of gas souring and storage. The gas transport mechanisms in nanopores including bulk gas transfer and adsorption‐gas surface diffusion were already investigated in pore‐scale models, but their effects on actual gas production of multistage fractured horizontal wells in SGRs are not clearly understood, which are crucial for the economic development of unconventional resources. Therefore, a comprehensive apparent permeability (AP) model which couples the surface diffusion of adsorbed gas, slippage flow considering the additional flux generated by surface diffusion based on Langmuir's theory, and Knudsen diffusion is established. The presented model is validated with the experimental data and lattice Boltzmann method (LBM) simulation results. Then, we propose a numerical model which combines multiflow mechanisms in microscale pores and a multistage fractured horizontal well (MSFHW) in macroscale shale gas reservoirs together. The effects of different transport mechanisms on both AP of nanopores and gas production are analyzed thoroughly. The results show that the effect of surface diffusion on the apparent permeability of nanopores is much greater than that on the actual gas production of MSFHW, and the influence of high‐pressure condition must be considered when calculating the surface diffusion coefficient. The presented numerical model has important implications for accurate numerical simulation and efficient development of shale gas reservoirs.

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An Integrative Model To Simulate Gas Transport and Production Coupled With Gas Adsorption, Non-Darcy Flow, Surface Diffusion, and Stress Dependence in Organic-Shale Reservoirs

Cited by 62 publications

References 29 publications

Effect of Permeability Anisotropy on the Production of Multi-Scale Shale Gas Reservoirs

Effect of Permeability Anisotropy on the Production of Multi-Scale Shale Gas Reservoirs

Multiscale Apparent Permeability Model of Shale Nanopores Based on Fractal Theory

A novel numerical model of gas transport in multiscale shale gas reservoirs with considering surface diffusion and Langmuir slip conditions

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