Laboratory scale research on the impact of stress shadow and natural fractures on fracture geometry during horizontal multi-staged fracturing in shale

Zhou, Jian; Zeng, Yanjun; Jiang, Tingxue; Zhang, Baoping

doi:10.1016/j.ijrmms.2018.03.007

Cited by 27 publications

(13 citation statements)

References 15 publications

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“…A concrete sample was fractured using two pumping systems to obtain two evenly and synchronously propagating fractures [24]. After improving the pumping system, multiple 300 mm × 600 mm × 300 mm shale samples were fractured to observe a single fracture could initiate and propagate in majority of cases [25]. Moreover, the stress shadow effect could not only inhibit the propagation of adjacent fractures but also lead to the bifurcation of adjacent fractures.…”

Section: Of 21mentioning

confidence: 99%

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Experimental Study on the Initiation and Propagation of Multi-Cluster Hydraulic Fractures within One Stage in Horizontal Wells

Wang

Yang

et al. 2021

Energies

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Competitive propagation of fractures initiated from multiple perforation clusters is universal in hydraulic fracturing of unconventional reservoirs, which largely influences stimulation. However, the propagation mechanism of multi-fractures has not been fully revealed for the lack of a targeted laboratory observation. In this study, a physical simulation experiment system was developed for investigating the initiation and propagation of multi-cluster hydraulic fractures. Different from the traditional hydro-fracking test system, the new one was equipped with a multi-channel shunting module and a strain monitoring system, which could guarantee the full fracture extension at each perforation clusters and measure the internal deformation of specimens, respectively. Several groups of true tri-axial fracturing tests were performed, considering the factors of in situ stress, cluster spacing, pumping rate, and bedding structures. The results showed that initiation of multi-cluster hydraulic fractures within one stage could be simultaneous or successive according to the difference of the breakdown pressure and fracturing fluid injection. For simultaneous initiation, the breakdown pressure of the subsequent fracture was lower than or equal to the value of the previous fracture. Multiple fractures tended to attract and merge. For successive initiation, the breakdown pressures of fractures were gradually increasing. The subsequent fracture tended to intersect with or deviated from the previous fracture. Multiple fractures interaction was aggravated by the decrease of horizontal stress difference, bedding number and cluster spacing, and weakened by the increase of pump rate. The propagation area of multiple fractures increased with the pump rate, decreased with the cluster spacing. The strain response characteristics corresponded with the initiation and propagation of fracture, which was conducive to understanding the process of the fracturing. The test results provide a basis for optimum design of hydraulic fracturing.

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Section: Of 21mentioning

confidence: 99%

“…Multi-staged fracturing in shale can result in single or two unbalanced fractures in the laboratory [25]. However, the formation of multiple fractures is random.…”

Section: Multiple Fractures Interactionmentioning

confidence: 99%

Experimental Study on the Initiation and Propagation of Multi-Cluster Hydraulic Fractures within One Stage in Horizontal Wells

Wang

Yang

et al. 2021

Energies

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“…Xu et al (2020) have established a reservoir pore evolution model based on reservoir diagenesis and quantitative evaluation of reservoir pores. And the reservoirs are divided into two categories: low porosity with low permeability and ultralow porosity with ultralow permeability [4]; have studied the multiple fracture interaction behavior of water-bearing and oil-bearing unsaturated reservoirs, which confirmed the importance of applying the two-phase flow process to multifracture interaction analysis and fracture trajectory function in the process of sandstone oil and gas development [5][6][7]; Yin et al (2020) have conducted further research on the pore structure and physical properties of sandstone, and the research showed that sandstone has the characteristics of strong dissolution, low cementation rate, weak cementation, high porosity, and high permeability [8,9]; Li et al (2020) have used nuclear magnetic resonance technology to determine the changes in the size and quantity of sandstone pores after high temperature treatment. And the development of cracks and changes in rock mechanical properties after high temperature treatment have been studied [10,11]; have observed and analyzed the dynamic failure and failure process of sandstone under cyclic impact load from a microscopic scale.…”

Section: Introductionmentioning

confidence: 99%

Dynamic Brittle Instability Characteristics of 2000 m Deep Sandstone Influenced by Mineral Composition

Hao

Chen

Wei

et al. 2021

Shock and Vibration

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The study of dynamic brittleness and failure characteristics is of guiding significance for promoting the full exploitation and utilization of deep sandstone reservoirs. At present, there have been more comprehensive studies on the mechanical properties of deep sandstone reservoirs, but the study of mineral composition on the dynamic brittleness and failure characteristics of deep sandstone reservoirs is relatively weak. In this paper, XRD mineral composition analysis, uniaxial compression experiment, and Brazilian splitting are used to study the influence of mineral composition on mechanical properties and failure characteristics of deep sandstone reservoirs. It was concluded that (1) the mineral compositions of deep sandstone reservoirs are mainly three kinds of oxides: SiO2, Al2O3, and CaO. The failure modes of deep sandstone reservoir samples under uniaxial compression are more complicated, with tension failure and shear failure each accounting for half. In the Brazilian split test, the failure modes of sandstone samples are mainly shear failure. (2) The compressive strength decreases obviously with the increase of CaO content. The contents of SiO2, Al2O3, and CaO all have a great influence on the residual strength of deep sandstone reservoirs. The deformation modulus decreases gradually with the increase of Al2O3 content. (3) The brittleness increases slightly when the content of SiO2 increases, while the brittleness decreases slightly when the content of Al2O3 increases. Considering factors such as strength, modulus, brittleness, and failure characteristics, SiO2 content has the greatest influence on the mechanical properties of deep sandstone reservoirs, followed by Al2O3 content, and CaO content has the least influence. The research results have a guiding role in the utilization and development of oil and gas resources in deep sandstone reservoirs and promote oil and gas development from the middle to deeper layers.

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“…Multistaged fracturing in the roof of outburst coal seam aims to create multiple fractures in the roof, which can traverse the coalrock interface for building migration channel for methane drainage [17]. erefore, the research emphasis on mechanism of permeability enhancement by multistaged fracturing in the roof of outburst coal seam mainly focuses on whether the multiple fractures in the roof can form and then traverse the coal-rock interface [18].…”

Section: Introductionmentioning

confidence: 99%

Theoretical Study and Numerical Simulation Research on the Effect of Coal-Rock Interface on Multistaged Fracturing in the Roof of Outburst Coal Seam

Zhai

Tang

2021

Shock and Vibration

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Multistaged fracturing in the roof of outburst coal seam is an efficient and creative technology for coalbed methane (CBM) drainage, which can effectively improve the permeability of coal seam. To reveal its mechanism of permeability enhancement, the effect of coal-rock interface on multistaged fracturing in the roof of outburst coal seam was simulated and discussed in this paper. Firstly, the lithological difference between outburst coal seam and roof was compared, and the concept and significance of multistaged fracturing in the roof of outburst coal seam were explained. Then, the mechanical conditions of multiple fractures in the roof traversing coal-rock interface were analyzed. The effects of mechanical parameters on multiple fractures were numerically simulated. The results indicated that fracturing borehole in adjacent rocks of outburst coal seam is much easier to drill and maintain gas drainage. Considering gas drainage efficiency and avoiding being blocked by coal fines, multistaged fracturing borehole is generally drilled in the stable rock stratum of roof. Whether the multiple fractures in the roof can traverse coal-rock interface is related to mechanical parameters of coal and rock, friction factor of coal-rock interface, angle between horizontal profile and coal-rock interface, cementing strength of coal-rock interface, minimum horizontal stress, and other factors. Higher fracturing fluid pressure contributes to propagating from the reservoir with low elastic modulus to the one with high elastic modulus for hydraulic fracture. Hydraulic fracture is more likely to propagate in the rock stratum with high brittleness index. The research results can improve multistaged fracturing theory and provide technological support for field test.

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Laboratory scale research on the impact of stress shadow and natural fractures on fracture geometry during horizontal multi-staged fracturing in shale

Cited by 27 publications

References 15 publications

Experimental Study on the Initiation and Propagation of Multi-Cluster Hydraulic Fractures within One Stage in Horizontal Wells

Experimental Study on the Initiation and Propagation of Multi-Cluster Hydraulic Fractures within One Stage in Horizontal Wells

Dynamic Brittle Instability Characteristics of 2000 m Deep Sandstone Influenced by Mineral Composition

Theoretical Study and Numerical Simulation Research on the Effect of Coal-Rock Interface on Multistaged Fracturing in the Roof of Outburst Coal Seam

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