Experimental study of the permeability of fractured sandstone under complex stress paths

Wang, Lu; Li, Hao; Zhang, Yan; Fu, Guangming

doi:10.1002/ese3.728

Cited by 11 publications

(7 citation statements)

References 32 publications

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“…As the formation pressure decreases, their stress sensitivity is stronger than conventional reservoirs (Figure 2). Many scholars have studied stress sensitivity effects in tight reservoirs through physical simulation experiments and numerical simulation techniques and have built corresponding permeability models [27][28][29]. Based on the relationship model between porosity and permeability, Mckee et al proposed an exponential model between permeability and effective stress using rock mechanics theory [30].…”

Section: Model Construction and Solutionmentioning

confidence: 99%

Pressure Response of a Horizontal Well in Tight Oil Reservoirs with Stimulated Reservoir Volume

Chen¹,

Pingguo³

et al. 2021

Lithosphere

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Stimulated reservoir volume is an effective stimulation measure and creates a complex fracture network, but the description and characterization of fracture network are very difficult. Well test analysis is a common method to describe the fracture network, and it is the key to build a proper interpretation model. However, most published works only consider the shape of the fractured area or the stress sensitivity effect, and few works take both factors into account. In this paper, based on reservoir properties and flow law after a stimulated reservoir volume, an interpretation model is established with an arbitrary shape of the fractured area and stress sensitivity effect of different flow areas. The model is solved to conduct the pressure response using Laplace transform, point source function, and boundary element theory. The influence of fractures’ parameters and stress sensitivity effect is analyzed on the pressure behavior. Results from this study show that the special flow regimes for a horizontal well with a stimulated reservoir volume are (1) bilinear flow dominated by hydraulic fractures, (2) linear flow dominated by formation around the hydraulic fractures, (3) crossflow from a matrix system to the fractured area, and (4) radial flow control by properties of the fractured area. Parameters of hydraulic fractures mainly affect the early stage of pressure behavior. On the contrary, the stress-sensitive effect mainly affects the middle and late stages; the stronger the stress sensitivity effect is, the more obvious the effect is. The findings of this study can help for better understanding of the fracture network in a tight oil reservoir with a stimulated reservoir volume.

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Section: Model Construction and Solutionmentioning

confidence: 99%

Pressure Response of a Horizontal Well in Tight Oil Reservoirs with Stimulated Reservoir Volume

Chen¹,

Pingguo³

et al. 2021

Lithosphere

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“…Compared to intact sandstone, single‐fracture sandstone, and double‐fracture sandstone have been found to have significantly greater permeability. This was determined in a study where the permeability of these three types of sandstone was compared 7 . Zhao et al 8 conducted research on the seepage behavior of fracture networks after hydraulic fracturing of shale and concluded that the seepage channels formed during the process can significantly enhance the permeability of shale.…”

Section: Introductionmentioning

confidence: 99%

“…This was determined in a study where the permeability of these three types of sandstone was compared. 7 Zhao et al 8 conducted research on the seepage behavior of fracture networks after hydraulic fracturing of shale and concluded that the seepage channels formed during the process can significantly enhance the permeability of shale. In addition, hydraulic fracturing is also used in the commercial development of oil and gas wells to increase production.…”

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confidence: 99%

Influences of confining pressure and injection rate on breakdown pressure and permeability in granite hydraulic fracturing

Zhang

Xie

2023

Energy Science & Engineering

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Hot dry rock (HDR) geothermal resource is a renewable green energy source with great exploitation potential. The burial depth of HDR generally exceeds 2500 m and is typically under high in situ stress conditions, resulting in an ultralow permeability of the rock formations. To enhance the permeability of these formations, hydraulic fracturing is widely used as a reservoir stimulation technique in HDR geothermal resource exploitation. The differences in burial depth, in situ stress, and geological environment require different engineering designs when implementing hydraulic fracturing. Therefore, the confining pressure and injection rate play significant roles in determining the effectiveness of hydraulic fracturing, as they affect the propagation and distribution of fractures in the rock formation. To quantify the impact of these factors on the effectiveness of hydraulic fracturing, simulation experiments, and permeability tests were conducted using granite specimens under various confining pressure and injection rate conditions. The results of these experiments revealed the relationships among the confining pressure, injection rate, breakdown pressure, and permeability enhancement of the granite. The breakdown pressure of granite increased with the confining pressure, while the injection rate had little effect on the breakdown pressure.The hydraulic fractured sample produced new penetrating fractures, which increased the reservoir permeability, and owing to the higher complexity of hydraulic fractures under low confining pressure, the increase of permeability is correspondingly higher. The research results can provide an important

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“…Studies have shown that the permeability of mudstone at room temperature is affected by triaxial stress and pore pressure, that is, it decreases with the i ncrease of effective stress [4][5][6][7][8][9]. Temperature also has a significant effect on th e permeability of rocks.…”

Section: Introductionmentioning

confidence: 99%

Effect of Temperature on Permeability of Mudstone Subjected to Triaxial Stresses and Its Application

Yu,

Dong,

Zhou

et al. 2023

Preprint

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To prevent the leakage of pyrolyzed oil and gas as well as the release of pollutants from the top and floor strata, it is crucial to conduct a comprehensive study on the seepage characteristics of these strata under high-temperature triaxial stress conditions. This study will help ensure the containment and integrity of subsurface reservoirs and storage environments. Mudstone, serving as both the upper and lower strata, offers an effective barrier due to its inherently low permeability. In order to explore the change rule of mudstone sealing performance under high temperature triaxial stress, an air-heated low permeability rock mass air permeability measurement system is used to measure the ground stress buried 500m deep and the temperature variation characteristics of mudstone permeability on the roof and floor of Jimsar oil shale in Xinjiang under 100℃. It was found that the permeability of stressed mudstone decreased with the temperature rising up to 100℃. The predominant factor was thermal expansion of mudstone. The drop value depended on triaxial stresses that large stresses could induce small drop value. The average hydraulic radius of pore in the mudstone was also calculated, which also exhibited continuous reduction as heating up to 100℃ and the degree of reduction could reach 68%. The capacity, that prevent oil & gas and contaminant from moving cross strata as a barrier, would be strengthened when the mudstone strata from roof and floor experienced the temperature low than 100℃. The barrier performance of mudstone as a pollutant migration barrier layer to gas pollutant migration during in-situ heat injection mining of oil shale was further evaluated.

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Experimental study of the permeability of fractured sandstone under complex stress paths

Cited by 11 publications

References 32 publications

Pressure Response of a Horizontal Well in Tight Oil Reservoirs with Stimulated Reservoir Volume

Pressure Response of a Horizontal Well in Tight Oil Reservoirs with Stimulated Reservoir Volume

Influences of confining pressure and injection rate on breakdown pressure and permeability in granite hydraulic fracturing

Effect of Temperature on Permeability of Mudstone Subjected to Triaxial Stresses and Its Application

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