A novel evaluation on fracture pressure in depleted shale gas reservoir

Zhao, Kai; Yuan, Junliang; Feng, Yongcun; Yan, Cheng

doi:10.1002/ese3.198

Cited by 15 publications

(8 citation statements)

References 39 publications

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“…During recent years, some scholars have employed rock specimens with a central hole for simulation of failure behavior of deep tunnels at a laboratory scale and focused on the quantitative characterization of stress concentration and crack propagation behavior around the holes investigated the failure properties of Iddefjord granite samples containing prefabricated holes under uniaxial compression tests at laboratory and numerical scales and rockburst phenomena such as rock block ejection, and slabbing failure similar to in situ measurements was observed around the prefabricated holes under high compressive stress.…”

Section: Introductionmentioning

confidence: 99%

Analysis of fractures of a hard rock specimen via unloading of central hole with different sectional shapes

Fan

Chen

et al. 2019

Energy Science & Engineering

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Hard rock failure and rockburst hazards under high in situ stresses have been the subject of deep rock mechanics and engineering. Previous investigations employed cubic rock specimens with a central hole for simulation of rock fracturing around deep tunnels at a laboratory scale, while the failure characteristics and crack evolution behavior around different shapes of holes induced by excavation unloading response have been barely considered. A commercially combined finite‐discrete element method (combined FEM/DEM) was used to investigate the failure characteristics and crack propagation process of typical hard rock specimens (marble) via the unloading of central hole with different shapes. Rock heterogeneity was also considered in the model in combination with the engineering reality. The combined FEM/DEM approach was first validated by simulating uniaxial compression and Brazilian tests. Then, the parametrical analysis was conducted in detail on the basis of five different sectional shapes of central holes, including a circle, ellipse, U‐shape, trapezoid, and cube, and two lateral pressure coefficients. Analysis of crack propagation paths, released strain energy, displacement, and average velocity distribution of the monitoring points around the central hole suggests that the failure degree and destruction intensity are strongly related to the sectional shape and lateral pressure coefficients. Hard and brittle rock failure induced by the excavation unloading effect can be classified as stable failure (slabbing failure) and unstable failure (strain rockburst). The cubic, trapezoidal, and U‐shaped holes within the specimen are the most likely to induce unstable failure, while stable failure is the dominant failure pattern around circular and elliptical holes. The lateral pressure coefficient λ was also found to affect failure position and intensity (only for the axisymmetric section) around the central hole. The influence of rock heterogeneity on failure intensity and range around the central hole within the specimen was also discussed. This study emphasizes the importance and necessity of the excavation unloading effect when evaluating surrounding rock failure around deep tunnels.

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Section: Introductionmentioning

confidence: 99%

Analysis of fractures of a hard rock specimen via unloading of central hole with different sectional shapes

Fan

Chen

et al. 2019

Energy Science & Engineering

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“…[1][2][3][4] In this process, transferred with the fracturing fluid, those solid proppants play an essential role in holding the fracture open and providing a high fracture conductivity, thus leading to an economic hydrocarbon extraction from the fractured unconventional pay zones. [1][2][3][4] In this process, transferred with the fracturing fluid, those solid proppants play an essential role in holding the fracture open and providing a high fracture conductivity, thus leading to an economic hydrocarbon extraction from the fractured unconventional pay zones.…”

Section: Introductionmentioning

confidence: 99%

“…To successfully stimulate the productivity of the lowpermeability unconventional reservoirs (eg, tight oil sandstones and gas shale reservoirs), hydraulic fracturing has been widely used to create tiny fractures and connect natural fractures by injecting highly pressurized fracturing fluid. [1][2][3][4] In this process, transferred with the fracturing fluid, those solid proppants play an essential role in holding the fracture open and providing a high fracture conductivity, thus leading to an economic hydrocarbon extraction from the fractured unconventional pay zones. [5][6][7] The proppant should have a high resistance to the fracture closure stress after decreasing the fracturing pressure, in case that they would be crushed under a tremendous value of loading.…”

Section: Introductionmentioning

confidence: 99%

Effect of surface wettability of ceramic proppant on oil flow performance in hydraulic fractures

Dong

Wang

2019

Energy Science & Engineering

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Ceramic proppants are critical products for holding induced fractures open and enhancing hydrogen productivity in low‐permeability reservoirs. Though the effects of proppant size and proppant type on the well productivity have been well studied in the past, the role of the proppant surface wettability in the oil flow performance has not been thoroughly investigated. To help the readers and the industries understand the wetting behavior of ceramic proppants, this research was designed to analyze the effect of the proppant wettability on the flow efficiencies of oil and water under different conditions (for example, various proppant size, water saturation, and waterflooding). Also, it was required to determine the optimal wettability of proppants in the available candidates for the enhancement of oil recovery in the hydraulic fracturing process. Results of the work indicate that the proppant wettability plays an essential role in the productivities of water and oil in tight sandstones. Compared with the same‐size oil‐wet proppants, the mixed‐wet proppants contribute to increasing the oil flow efficiency and reducing the produced volume of water. However, an increased value of proppant size can significantly enhance the oil recovery. Besides, using the oil‐wet proppants, the waterflooding phenomenon can lead to a lower oil recovery than that of the non‐water‐flooded specimen. Based on the findings of the microscopic structural characteristics of the proppant surface, a fluid channel mechanism was proposed to help understand the proppant wettability effect on the flow behaviors of oil and water. This research can provide guidance on the determination of proppants in the designs of hydraulic fracturing operations. These findings can help the reservoir engineers dealing with hydraulic fracturing better design the surface wettability of the proppants, especially for those reservoirs with a multi‐phase flow.

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“…Devido às redes de nanoporos dos reservatórios de gás de folhelho, o fluxo convencional da equação de Darcy não descreve com acuracidade o transporte de gás (Javadpour et al, 2007). Considerando as redes de fraturas naturais, a nanoescala dos poros e as formas de armazenamento de gás, o transporte de gás nesses reservatórios pode compreender uma combinação de diferentes mecanismos, como fluxo viscoso, difusão de Knudsen e difusão de superfície, bem como a adsorção/dessorção do gás (Zhao et al, 2018), ilustrados na Figura 9.…”

Section: Mecanismos De Difusãounclassified

“…Figura 9. Diagrama esquemático do transporte de gás em reservatórios de gás de folhelho em nanoescala (Zhao et al, 2018).…”

Section: Mecanismos De Difusãounclassified

Armazenamento geológico de carbono em reservatórios não convencionais na Formação Irati da Bacia do Paraná: estimativas de capacidade de injeção de CO2 e custos associados

Masulino¹

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A novel evaluation on fracture pressure in depleted shale gas reservoir

Cited by 15 publications

References 39 publications

Analysis of fractures of a hard rock specimen via unloading of central hole with different sectional shapes

Analysis of fractures of a hard rock specimen via unloading of central hole with different sectional shapes

Effect of surface wettability of ceramic proppant on oil flow performance in hydraulic fractures

Armazenamento geológico de carbono em reservatórios não convencionais na Formação Irati da Bacia do Paraná: estimativas de capacidade de injeção de CO2 e custos associados

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