Effect of low-velocity non-Darcy flow on well production performance in shale and tight oil reservoirs

Wang, Xiukun; Sheng, James J.

doi:10.1016/j.fuel.2016.11.040

Cited by 120 publications

(53 citation statements)

References 18 publications

(21 reference statements)

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“…It is difficult to obtain the analytical solution of the partial differential equation with a strong nonlinear term and variable coefficient. So, the finite difference method [16] is used to solve the model of the volume fracturing vertical well considering the stress sensitivity and low-velocity non-Darcy flow. The flow coefficient term is treated explicitly and changed with the pressure.…”

Section: Geofluidsmentioning

confidence: 99%

“…In other words, the fracture and reservoir all are stress sensitivity medium [12][13][14]. In addition, due to the tiny porous and ultralow permeability of tight reservoirs, the flow in tight reservoirs obeys the law of low-velocity non-Darcy flow instead of Darcy flow [15], which is the fact that the flow velocity in a low pressure gradient regime is lower than what is estimated from Darcy's law [16].…”

Section: Introductionmentioning

confidence: 96%

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Pressure Analysis for Volume Fracturing Vertical Well considering Low-Velocity Non-Darcy Flow and Stress Sensitivity

Cui

Trivedi

et al. 2019

Geofluids

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In general, there is stress sensitivity damage in tight reservoirs and fractures. Furthermore, the flow in tight reservoirs is the lowvelocity non-Darcy flow. Currently, few researches of pressure analysis for volume fracturing vertical well are conducted simultaneously considering the low-velocity non-Darcy flow and stress sensitivity. In the paper, a novel flow model of a volume fractured vertical well is proposed and solved numerically. Firstly, the threshold pressure gradient, permeability modulus, and experimental data are, respectively, utilized to characterize the low-velocity non-Darcy flow, matrix stress sensitivity, and fracture stress sensitivity. Then, a two-region composite reservoir is established to simulate the vertical well with volume fracturing. After that, the logarithm meshing method is used to discrete the composite reservoir, and the flow model is solved by the method of finite difference and IMPES. Finally, the model verification is conducted, and the effects of the low-velocity non-Darcy flow and stress sensitivity on the pressure and pressure derivative are analyzed. The six flow regimes are identified by the dimensionless pressure and pressure derivative curve. They are, respectively, the fracture linear flow regime, early transition flow regime, radial flow regime, crossflow regime, advanced transition flow regime, and boundary controlling flow regime. The stress sensitivity and threshold pressure gradient have a great effect on the dimensionless pressure and pressure derivative. With the increase of reservoir stress sensitivity, the pressure and pressure derivative are upward at the advanced transition flow and boundary controlling regimes. However, the pressure and pressure derivative are downward at the advanced transition flow and boundary controlling regimes when the fracture sensitivity increases. An increase in the threshold pressure gradient results in a high dimensionless pressure and pressure derivative. This work reveals the effects of low-velocity non-Darcy flow and stress sensitivity on pressure and provides a more accurate reference for reservoir engineers in pressure analysis when developing a tight reservoir by using the volume fracturing vertical well.

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Section: Geofluidsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

Pressure Analysis for Volume Fracturing Vertical Well considering Low-Velocity Non-Darcy Flow and Stress Sensitivity

Cui

Trivedi

et al. 2019

Geofluids

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“…It is well known Darcy flow assumes that the flow velocity-pressure gradient relationship is a straight line which passes through the origin. Recently, many non-Darcy flow phenomena are found in low-permeability media [1,2], tight carbonate oil and gas reservoirs [3], shale oil and gas reservoirs [4,5], and clay soil [6]. Non-Darcy flow indicates that the flow velocity-pressure gradient relationship is not a straight line, also called nonlinear flow in porous media.…”

Section: Introductionmentioning

confidence: 99%

Analytical Solutions for Non-Darcy Transient Flow with the Threshold Pressure Gradient in Multiple-Porosity Media

Luo

Xiao-dong

et al. 2019

Mathematical Problems in Engineering

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Low-velocity non-Darcy flow can be described by using the threshold pressure gradient (TPG) in low-permeability porous media. The existence of the TPG yields a moving boundary so that fluid starts to flow inside this boundary when the pressure gradient overcomes the viscous forces, and beyond this boundary, there will be no flow. A mathematical model of considering the TPG is developed to describe the flow mechanism in multiple-porosity media. By defining new dimensionless variables, the nonlinear mathematical model can be solved analytically. This new approach has been validated with several approximate formulas and numerical tools. The diffusion of the moving boundary varying with time is analyzed in detail in multiple-porosity media, and then the effect of the moving boundary on pressure transient response is investigated and compared with that of the traditional three boundary types (closed boundary, infinite-pressure boundary, and constant-pressure boundary). Sensitivity analysis is conducted to study the effect of the TPG on pressure and pressure derivative curves and rate decline curves for single-porosity media, dual-porosity media, and triple-porosity media, respectively. The results show that the moving boundary exerts a significant influence on reservoir performance at a relatively early time, unlike the other three boundary types, and only a boundary-dominated effect at the late time. The larger the threshold pressure gradient, the smaller the diffusion distance of the moving boundary and the rate of this well at a given dimensionless time. At the same time, the pressure transient response exhibits a higher upward trend because of a larger TPG. All behavior response might be explained by more pressure drop consumed in low-permeability reservoirs. The finding is helpful to understand the performance of low-permeability multiple-porosity media and guide the reasonable development of low-permeability reservoirs.

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“…8,9 Experiments also were conducted to measure the thickness of boundarylayers and investigate the effect of boundary-layer on effective liquid permeability. 6,[11][12][13][14][15][16] The experiment results showed that the thickness of boundarylayer is related to pressure gradient, fluid viscosity, pore radius and fluid type. 11 With nanoscale simulation using dissipative particle dynamics and experimental data published in literatures, Cao et al 9 proposed an empirical equation to calculate boundary-layer thickness, and assuming that pore size distribution can be represented with Gaussian function, the authors developed a permeability model for tight oil reservoirs coupling boundarylayer effect.…”

Section: Introductionmentioning

confidence: 99%

A Fractal Permeability Model Coupling Boundary-Layer Effect for Tight Oil Reservoirs

et al. 2017

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A fractal permeability model coupling non-flowing boundary-layer effect for tight oil reservoirs was proposed. Firstly, pore structures of tight formations were characterized with fractal theory. Then, with the empirical equation of boundary-layer thickness, Hagen-Poiseuille equation and fractal theory, a fractal torturous capillary tube model coupled with boundary-layer effect was developed, and verified with experimental data. Finally, the parameters influencing effective liquid permeability were quantitatively investigated. The research results show that effective liquid permeability of tight formations is not only decided by pore structures, but also affected by boundary-layer distributions, and effective liquid permeability is the function of fluid type, fluid viscosity, pressure gradient, fractal dimension, tortuosity fractal dimension, minimum pore radius and maximum pore radius. For the tight formations dominated with nanoscale pores, boundary-layer effect can significantly reduce effective liquid permeability, especially under low pressure gradient.

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Effect of low-velocity non-Darcy flow on well production performance in shale and tight oil reservoirs

Cited by 120 publications

References 18 publications

Pressure Analysis for Volume Fracturing Vertical Well considering Low-Velocity Non-Darcy Flow and Stress Sensitivity

Pressure Analysis for Volume Fracturing Vertical Well considering Low-Velocity Non-Darcy Flow and Stress Sensitivity

Analytical Solutions for Non-Darcy Transient Flow with the Threshold Pressure Gradient in Multiple-Porosity Media

A Fractal Permeability Model Coupling Boundary-Layer Effect for Tight Oil Reservoirs

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