Effect of low velocity non-Darcy flow on pressure response in shale and tight oil reservoirs

Diwu, Pengxiang; Liu, Tongjing; You, Zhenjiang; Jiang, Baoyi; Jian, Zhou

doi:10.1016/j.fuel.2017.11.041

Cited by 62 publications

(18 citation statements)

References 36 publications

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“…The typical pre‐Darcy flow curve is a combination of a straight line and a concave curve (Dejam et al, 2017). The intersection acquired by extrapolating the linear part of the flow curve to the coordinate axis is defined as the pseudo TPG ( G P ) (Diwu et al, 2018; Zeng et al, 2018), which can be used to characterize the degree of solid‐water interaction and non‐Darcian flow behavior (Liu & Birkholzer, 2012). Accordingly, the G P in this experiment was obtained by linear fitting of the linear part of the flow curve.…”

Section: Methodsmentioning

confidence: 99%

“…On the one hand, many scholars corroborated the existence of a TPG through experiments on compacted clay (or tight rocks) and discussed the effects of clay content, temperature, permeability, and fluid types on this TPG (Miller & Low, 1963; Prada & Civan, 1999; Wang et al, 2016; Zeng et al, 2012). The TPG also has been applied to construct flow models (Dejam et al, 2017; Diwu et al, 2018; Zeng et al, 2018). On the other hand, some researchers believe that the TPG does not exist and attribute this phenomenon to experimental errors, such as the entrapped air and the errors in measurement of low flow rates and low pressure gradients (Kutilek, 1972; Olsen, 1966; Wang & Sheng, 2017).…”

Section: Introductionmentioning

confidence: 99%

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Experimental Investigation on the Movability of Water in Shale Nanopores: A Case Study of Carboniferous Shale From the Qaidam Basin, China

Yang

2020

Water Resources Research

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The movability of water in shale nanopores intensely affects the transport and storage of other fluids and plays an important role in the geological water cycle. To investigate the movability of water, three shale samples were used to conduct flow experiments using the steady state and step‐by‐step depressurization method. The experimental results show that the movability of water strongly depends on the pressure gradient. Two water‐related mechanisms, shear fluidity and electroviscous effect, are primarily responsible for the difference in movability between free water and bound water. The flow of water in these samples deviates from Darcy's law, and the threshold pressure gradient (TPG) is observed. When the pressure gradient is higher than the TPG, water starts to flow, and the permeability increases with increasing pressure gradient. Based on the analysis of the solid‐liquid interfacial forces, the water in the shale was quantitatively classified into four types (L1, L2, L3, and L4) according to its movability. The calculation results indicate that most of the water, which could be up to 74.46–89.73%, is immovable under the experimental conditions. The proportion of movable water increases with increasing pressure gradient, and the relation can be expressed by a quadratic function. The moving ratio was defined as the ratio of the volume of water involved in flow to the total pore volume. The correlation between the moving ratio and permeability is a power function with exponents ranging from 1.16 to 1.43, indicating that water permeability is sensitive to the moving ratio.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Experimental Investigation on the Movability of Water in Shale Nanopores: A Case Study of Carboniferous Shale From the Qaidam Basin, China

Yang

2020

Water Resources Research

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“…Wang and Sheng (2017a, b) suggested that the non-Darcy flow of low-velocity profile greatly affects the well production performance. Cao et al (2018) offered a composite transient model for horizontal well testing while Diwu et al (2018) developed a model for well test pressure transient analysis by incorporating the TPG. Even some scholars offered mathematical production models for heterogeneous tight reservoirs (Chen and Durlofsky 2006;Wang et al 2018;Wu et al 2006) and some have also worked on relative permeability, water saturation and capillary pressure considering the heterogeneity of porous media.…”

Section: Introductionmentioning

confidence: 99%

Tight gas production model considering TPG as a function of pore pressure, permeability and water saturation

Zafar

et al. 2020

Pet. Sci.

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Threshold pressure gradient has great importance in efficient tight gas field development as well as for research and laboratory experiments. This experimental study is carried out to investigate the threshold pressure gradient in detail. Experiments are carried out with and without back pressure so that the effect of pore pressure on threshold pressure gradient may be observed. The trend of increasing or decreasing the threshold pressure gradient is totally opposite in the cases of considering and not considering the pore pressure. The results demonstrate that the pore pressure of tight gas reservoirs has great influence on threshold pressure gradient. The effects of other parameters like permeability and water saturation, in the presence of pore pressure, on threshold pressure gradient are also examined which show that the threshold pressure gradient increases with either a decrease in permeability or an increase in water saturation. Two new correlations of threshold pressure gradient on the basis of pore pressure and permeability, and pore pressure and water saturation, are also introduced. Based on these equations, new models for tight gas production are proposed. The gas slip correction factor is also considered during derivation of this proposed tight gas production models. Inflow performance relationship curves based on these proposed models show that production rates and absolute open flow potential are always be overestimated while ignoring the threshold pressure gradients.

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“…The characteristics of low permeability reservoirs makes it necessary to use artificial fracturing technology during the development of the reservoir. The artificial fractures formed by artificial fracturing can connect with natural fractures, thus the development efficiency of low permeability oil reservoirs will significantly increase (Fletcher et al, 1992 ; Diwu et al, 2018 ). However, the permeability of these fractures will gradually become higher after the long-term injection of water, and that will improve the heterogeneity of low permeability oil reservoirs (Zhao et al, 2018 ).…”

Section: Introductionmentioning

confidence: 99%

Field Application of Nanoscale Polymer Microspheres for In-Depth Profile Control in the Ultralow Permeability Oil Reservoir

Hou

Zhao

Jia³

et al. 2020

Front. Chem.

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Much research has been carried out on nanoscale polymer microspheres (PMs) in laboratories in recent years. However, there are limited reports on the practical application of nanoscale PMs in ultralow permeability reservoirs. This paper reports a field application case of nanoscale PMs for in-depth profile control in the ultralow permeability oil reservoir. In the paper, the characteristics of the reservoir and the problems faced during development are analyzed in detail. Then, the PMs with calibration diameters of 300 nm and 800 nm are researched by evaluation experiments, and are selected for in-depth profile control in the ultralow permeability oil reservoir. Finally, according to the effect of the pilot application, the performance of PMs is evaluated, and a more suitable size for the pilot test reservoir is determined. The experiment's results show that the PMs have a good capacity for swelling and plugging. For the PMs with a calibration diameter of 300 nm, the final equilibrium swelling ratio is 56.2 nm·nm −1 , and the maximum resistance coefficient and the blocking rate after swelling are 3.7 and 70.31%, respectively. For the PMs with a calibration diameter of 800 nm, the final equilibrium swelling ratio is 49.4 nm·nm −1 , and the maximum resistance coefficient the blocking rate after swelling are 3.5 and 71.42%, respectively. The performance evaluation results show that nanoscale PMs can be used for in-depth profile control in the ultralow permeability oil reservoir. After the application of PMs in the pilot test area, the average water cut decreased by 10.4%, the average liquid production of single well-increased by 0.9 t/d, and the average thickness of the water-absorbing layer increased by 1.77 m. Comparing the dynamic data variation of well-groups using the PMs with the calibration diameter as 800 nm and the calibration diameter as 300 nm, it indicates that, for the pilot test area, PMs with a calibration diameter of 300 nm are more suitable than PMs with a calibration diameter of 800 nm.

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Effect of low velocity non-Darcy flow on pressure response in shale and tight oil reservoirs

Cited by 62 publications

References 36 publications

Experimental Investigation on the Movability of Water in Shale Nanopores: A Case Study of Carboniferous Shale From the Qaidam Basin, China

Experimental Investigation on the Movability of Water in Shale Nanopores: A Case Study of Carboniferous Shale From the Qaidam Basin, China

Tight gas production model considering TPG as a function of pore pressure, permeability and water saturation

Field Application of Nanoscale Polymer Microspheres for In-Depth Profile Control in the Ultralow Permeability Oil Reservoir

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