Pseudo threshold pressure gradient to flow for low permeability reservoirs

Xiong, Wei; Lei, Qun; Gao, Shusheng; Hu, Zhiming; Hui, Xue

doi:10.1016/s1876-3804(09)60123-3

Cited by 126 publications

(33 citation statements)

References 3 publications

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“…This is the pressure gradient that must be exceeded before flow is observed. A pressure gradient has been shown to exist when whetting a previously dry sample, [36,33], or for swelling soils such as clay [32]. In this paper, we demonstrated that concentration gradients are negligible, if the pressure is the pressure of a reservoir in electro-chemical equilibrium with the swelling porous media, p B , then there is no pressure threshold gradient.…”

Section: Discussionmentioning

confidence: 65%

Macroscopic Flow Potentials in Swelling Porous Media

Schreyer-Bennethum

2012

Transp Porous Med

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In swelling porous media, the potential for flow is much more than pressure, and derivations for flow equations have yielded a variety of equations. In this paper we show that the macroscopic flow potentials are the electro-chemical potentials of the components of the fluid and that other forms of flow equations, such as those derived through mixture theory or homogenization, are a result of particular forms of the chemical potentials of the species. It is also shown that depending upon whether one is considering the pressure of a liquid in a reservoir in electro-chemical equilibrium with the swelling porous media, or the pressure of the vicinal liquid within the swelling porous media, a critical pressure gradient threshold exists or does not.

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Section: Discussionmentioning

confidence: 65%

Macroscopic Flow Potentials in Swelling Porous Media

Schreyer-Bennethum

2012

Transp Porous Med

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“…: Porosity : Viscosity, mPa⋅s : Threshold pressure gradient : Fluid density, g/cm gsc , wsc : Density of gas and water under standard surface conditions, g/cm 3 .…”

Section: Greek Symbolsmentioning

confidence: 99%

“…The theories and models regarding the effect of TPG on water-oil two-phase flow have been proposed [1][2][3][4][5][6], and experiments were conducted to study the pseudo-TPG and analyze the reason for which the pseudo-TPG has to be overcome for flow in ultra-low permeability tight reservoirs [3,7,8]. However, less attention has been paid to the effect of water saturation on TPG of gas phase, especially for waterbearing tight gas reservoirs.…”

Section: Introductionmentioning

confidence: 99%

Gas-Water Flow Behavior in Water-Bearing Tight Gas Reservoirs

Cao

Lei

et al. 2017

Geofluids

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Some tight sandstone gas reservoirs contain mobile water, and the mobile water generally has a significant impact on the gas flowing in tight pores. The flow behavior of gas and water in tight pores is different than in conventional formations, yet there is a lack of adequate models to predict the gas production and describe the gas-water flow behaviors in water-bearing tight gas reservoirs. Based on the experimental results, this paper presents mathematical models to describe flow behaviors of gas and water in tight gas formations; the threshold pressure gradient, stress sensitivity, and relative permeability are all considered in our models. A numerical simulator using these models has been developed to improve the flow simulation accuracy for water-bearing tight gas reservoirs. The results show that the effect of stress sensitivity becomes larger as water saturation increases, leading to a fast decline of gas production; in addition, the nonlinear flow of gas phase is aggravated with the increase of water saturation and the decrease of permeability. The gas recovery decreases when the threshold pressure gradient (TPG) and stress sensitivity are taken into account. Therefore, a reasonable drawdown pressure should be set to minimize the damage of nonlinear factors to gas recovery.

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“…For the low permeability formation, fluid flow in reservoir has some special characteristics which can be summarized as follows: (1) flow departures from Darcy's law at low-velocity fluid flow. Many authors have noted the departures from Darcy's law in porous media through experiment methods [1][2][3][4][5][6] and they found that the flow curve is a combination of a straight line and a concave curve. Non-Darcy's flow exists in low permeability porous media in which the TPG always can be observed.…”

Section: Introductionmentioning

confidence: 99%

Nonlinear Flow Characteristics and Horizontal Well Pressure Transient Analysis for Low-Permeability Offshore Reservoirs

Jiang

Teng

2015

Mathematical Problems in Engineering

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Threshold pressure gradient (TPG) and stress sensitivity which cause the nonlinear flow in low permeability reservoirs were carried out by experiments. Firstly, the investigation of existing conditions of TPG for oil flow in irreducible water saturation low-permeability reservoirs was conducted and discussed, using the cores from a real offshore oilfield in China. The existence of TPG was proven. The relationship between TPG and absolute permeability was obtained by laboratory tests. TPG increases with decreasing absolute permeability. Then, stress sensitivity experiment was carried out through depressurizing experiment and step-up pressure experiment. Permeability modulus which characterizes stress sensitivity increases with decreasing absolute permeability. Consequently, a horizontal well pressure transient analysis mathematical model considering threshold pressure gradient and stress sensitivity was established on the basis of mass and momentum conservation equations. The finite element method (FEM) was presented to solve the model. Influencing factors, such as TPG, permeability modulus, skin factor, wellbore storage, horizontal length, horizontal position, and boundary effect on pressure and pressure derivative curves, were also discussed. Results analysis demonstrates that the pressure transient curves are different from Darcy’s model when considering the nonlinear flow characteristics. Both TPG and permeability modulus lead to more energy consumption and the reservoir pressure decreases more than Darcy’s model.

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Pseudo threshold pressure gradient to flow for low permeability reservoirs

Cited by 126 publications

References 3 publications

Macroscopic Flow Potentials in Swelling Porous Media

Macroscopic Flow Potentials in Swelling Porous Media

Gas-Water Flow Behavior in Water-Bearing Tight Gas Reservoirs

Nonlinear Flow Characteristics and Horizontal Well Pressure Transient Analysis for Low-Permeability Offshore Reservoirs

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