A FEM-DFN model for the interaction and propagation of multi-cluster fractures during variable fluid-viscosity injection in layered shale oil reservoir

Huang, Chuhao; Zhu, Hehua; Wang, Jiandong; Han, Jian; Zhou, Guangqing; Tang, Xuanhe

doi:10.1016/j.petsci.2022.06.007

Cited by 20 publications

(6 citation statements)

References 33 publications

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“…In addition, because the fracture-cavity distribution and the in situ stress are formation attributes that cannot be altered, better stimulation effectiveness can be realized by controlling fluid viscosity and displacement, the type of fracturing fluid and other engineering design parameters. Given the constraints of field conditions, modifying fluid viscosity represents a practical approach to enhance fracturing efficiency [67]. For this reason, a comprehensive fracturing conception-variable fluid viscosity conception-was proposed (Figure 10).…”

Section: Discussionmentioning

confidence: 99%

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Experimental Investigation into the Process of Hydraulic Fracture Propagation and the Response of Acoustic Emissions in Fracture–Cavity Carbonate Reservoirs

Yang,

Wang,

et al. 2024

Processes

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Fracture–cavity carbonate reservoirs account for a considerable proportion of oil and gas resources. Because of the complicated relationships between cavities, fractures and pores in these reservoirs, which are defined as cavity clusters, fracturing technology is employed to enhance their hydrocarbon productivity. However, almost all previous studies have just considered the effect of a single natural cavity or fracture on the propagation of a hydraulic fracture; therefore, the mechanism by which a hydraulic fracture interacts with a cavity cluster needs to be clarified. In this study, cavity clusters with different distributions were accurately prefabricated in synthetically made samples, and large-scale simulation equipment was employed to systematically perform fracturing experiments considering different horizontal differential stress levels. Meanwhile, the hydraulic fracture propagation behaviors were comprehensively analyzed through fracture morphology, fracturing curves, the complexity of the fracture network and acoustic emission monitoring. It was found that a natural fracture with a smaller approach angle is favorable in guiding a hydraulic fracture to a cavity. The fracturing curves were divided into the following four types: frequent fluctuations with “step-like” shapes, great fluctuations with slightly lower closure pressure, fluctuations with obviously lower closure pressure, and little fluctuations with obviously lower closure pressure. And different cavity cluster distributions play a dominant role in the complexity of generated hydraulic fracture networks. In addition, AE energy was used to judge the ease of crossing the cavity. The above findings indicated that for the actual exploration and exploitation of carbonate reservoirs, the geological exploration of different fracture–cavity structures in reservoirs would be required, and targeted fracturing engineering designs need to be carried out for different fracture–cavity carbonate reservoirs.

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Section: Discussionmentioning

confidence: 99%

“…turing fluid and other engineering design parameters. Given the constraints of field conditions, modifying fluid viscosity represents a practical approach to enhance fracturing efficiency [67]. For this reason, a comprehensive fracturing conception-variable fluid viscosity conception-was proposed (Figure 10).…”

Section: Discussionmentioning

confidence: 99%

Experimental Investigation into the Process of Hydraulic Fracture Propagation and the Response of Acoustic Emissions in Fracture–Cavity Carbonate Reservoirs

Yang,

Wang,

et al. 2024

Processes

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“…Explicit representation allows for a detailed characterization of the fracture network and captures the impact of individual fractures on flow and transport behavior (Hirthe & Graf, 2015). The incorporation of explicit fracture representation fosters more accurate modeling, encapsulating the behavior of fluid flow affected by both the characteristics of fractures and variations in fluid viscosity (Huang et al., 2022).…”

Section: Related Workmentioning

confidence: 99%

An Analytical Solution for Variable Viscosity Flow in Fractured Media: Development and Comparative Analysis With Numerical Simulations

Younes,

Rajabi,

Rezaiezadeh Roukerd

et al. 2024

Water Resources Research

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Explicit fracture models often use analytical solutions for predicting flow in fractured media, usually assuming uniform fluid viscosity for simplicity. This assumption, however, can be inaccurate as fluid viscosity varies due to factors like composition, temperature, and dissolved substances. Our study, recognizing these discrepancies, abandons this uniform viscosity assumption for a more realistic model of variable viscosity flow, focusing on viscous displacement scenarios. This includes instances like injecting viscous surfactants for hydrocarbon recovery in fractured reservoirs or soil decontamination. This presents a significant challenge, enhancing our understanding of transport within fractures, mainly governed by advection. Our study centers on a low‐permeability rock matrix intersected by two fractures with variable apertures. We employ two methods: an analytical approach with a new solution and numerical simulations with two distinct in‐house codes, discretizing both the rock matrix and fractures with two‐dimensional triangular elements. The first code uses a Discontinuous Galerkin finite element method, while the second utilizes a finite‐volume method, allowing a comprehensive comparison of solutions. Additionally, we investigate parameter identifiability, like fracture apertures and viscosity ratios, using breakthrough curves from our analytical solution, applying the Markov Chain Monte Carlo technique.

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“…In previous studies, researchers used the finite element method (FEM) to simulate fracture generation processes. In this method, the cohesive zone model (CZM), which is commonly used to describe fracture initiation and propagation, obeys a law called "traction-separation" [26][27][28][29][30][31][32]. Guo et al [26] established a three-dimensional model to study the simultaneous generation of multiple fractures in shale reservoirs with a thick pay zone.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of the Simultaneous Development of Multiple Fractures in Horizontal Wells Based on the Extended Finite Element Method

Ping,

Zhao,

Zhu

et al. 2024

Energies

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Simultaneous multiple-fracture treatments in horizontal wellbores have become an essential technology for the economic development of shale gas reservoirs. During hydraulic fracturing, fracture initiation and propagation always induce additional stresses on the surrounding rock. When multiple fractures develop simultaneously, the development of some fractures is limited due to the stress-shadow effect. An in-depth understanding of the multiple-fracture propagation mechanism as reflected by fracture morphology and flow rate distribution can help to set reasonable operation parameters for improving the uniformity of multiple fractures and forming a complex fracture network according to the different in situ stress conditions in a reservoir to increase the shale gas recovery and reduce the cost. In this study, a two-dimensional (2D) fracture propagation model was developed based on the extended finite element method (XFEM). Then, the influences of various factors, including geological and operational factors, on the development of multiple fractures were studied. The results of numerical simulations showed that increasing the cluster spacing or injecting fracturing fluid with lower viscosity can help reduce the stress-shadow effect. In the case of smaller in situ stress differences, the deflection of the fractures was larger due to the stress-shadow effect. As the stress difference increased, the direction of the propagation of the fracture was gradually biased towards the direction of maximum horizontal stress. In addition, the injection rate had some effects on the fracture morphology and flow rate distribution. However, as the injection rate increased, the dominant fracture developed rapidly, and the fracture length significantly increased.

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A FEM-DFN model for the interaction and propagation of multi-cluster fractures during variable fluid-viscosity injection in layered shale oil reservoir

Cited by 20 publications

References 33 publications

Experimental Investigation into the Process of Hydraulic Fracture Propagation and the Response of Acoustic Emissions in Fracture–Cavity Carbonate Reservoirs

Experimental Investigation into the Process of Hydraulic Fracture Propagation and the Response of Acoustic Emissions in Fracture–Cavity Carbonate Reservoirs

An Analytical Solution for Variable Viscosity Flow in Fractured Media: Development and Comparative Analysis With Numerical Simulations

Numerical Simulation of the Simultaneous Development of Multiple Fractures in Horizontal Wells Based on the Extended Finite Element Method

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