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Numerical Analysis of Perforation during hydraulic Fracture Initiation Based on Continuous-Discontinuous Element Method

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Computer Modeling in engineering & Sciences 2024年第8期140卷 2103-2129页

作者： Rui Zhang Lixiang Wang Jing Li Chun Feng Yiming Zhang School of civil and Transportation engineering Hebei University of TechnologyTianjin300401China Key Laboratory for Mechanics in Fluid Solid Coupling Systems Institute of MechanicsChinese Academy of SciencesBeijing100190China School of civil engineering and Architecture Zhejiang Sci-Tech UniversityHangzhou310018China Jinyun Institute Zhejiang Sci-Tech UniversityLishui321400China

Perforation is a pivotal technique employed to establish main flow channels within the reservoir formation at the outset of hydraulic fracturing *** perforation designs is critical for augmenting the efficacy of hydraulic fracturing and boosting oil or gas *** this study,we employ a hybrid finite-discrete element method,known as the continuous–discontinuous element method(CDEM),to simulate the initiation of post-perforation hydraulic fractures and to derive enhanced design *** model incorporates the four most prevalent perforation geometries,as delineated in an engineering technical ***-world perforations deviate from the ideal cylindrical shape,exhibiting variable cross-sectional profiles that typically manifest as an initial constriction followed by an expansion,a feature consistent across all four perforation *** simulations take into account variations in perforation hole geometries,cross-sectional diameters,and perforation *** findings show that perforations generated by the 39g DP3 HMX perforating bullet yield the lowest breakdown pressure,which inversely correlates with increases in sectional diameter and perforation ***,this study reveals the relationship between breakdown pressure and fracture degree,providing valuable insights for engineers and designers to refine perforation strategies.

关键词： hydraulic fracturing real perforation shape breakdown pressure perforation layout design CDEM

Predicting impact forces on pipelines from deep-sea fluidized slides:A comprehensive review of key factors

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International Journal of Mining Science and Technology 2024年第2期34卷 211-225页

作者： Xingsen Guo Ning Fan Defeng Zheng Cuiwei Fu Hao Wu Yanjun Zhang Xiaolong Song Tingkai Nian State Key Laboratory of Coastal and Offshore engineering Dalian University of TechnologyDalian 116024China Department of civil Environmentaland Geomatic EngineeringUniversity College LondonLondon WC1E 6BTUnited Kingdom Shandong Provincial Key Laboratory of Marine Environment and Geological engineering Ocean University of ChinaQingdao 266100China State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Chengdu University of TechnologyChengdu 610059China College of civil engineering and Architecture Wenzhou UniversityWenzhou 325035China Key Laboratory of engineering and Technology for Soft Soil Foundation and Tideland Reclamation of Zhejiang Province Wenzhou 325035China Zhejiang International Science and Technology Cooperation Base of Ultra-soft Soil engineering and Smart Monitoring Wenzhou 325035China School of Geography Liaoning Normal UniversityDalian 116029China China Railway First Survey and Design Institute Group Co. Ltd.Xi’an 710043China Department of Geotechnical engineering Nanjing Hydraulic Research InstituteNanjing 210024China Wuhan Center China Geological Survey(Central South China Innovation Center for Geosciences)Wuhan 430205China State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines Anhui University of Science and TechnologyHuainan 232001China

Deep-sea pipelines play a pivotal role in seabed mineral resource development,global energy and resource supply provision,network communication,and environmental ***,the placement of these pipelines on the seabed surface exposes them to potential risks arising from the complex deep-sea hydrodynamic and geological environment,particularly submarine *** incidents have highlighted the substantial damage to pipelines due to ***,deep-sea fluidized slides(in a debris/mud flow or turbidity current physical state),characterized by high speed,pose a significant *** assessing the impact forces exerted on pipelines by fluidized submarine slides is crucial for ensuring pipeline *** study aimed to provide a comprehensive overview of recent advancements in understanding pipeline impact forces caused by fluidized deep-sea slides,thereby identifying key factors and corresponding mechanisms that influence pipeline impact *** factors include the velocity,density,and shear behavior of deep-sea fluidized slides,as well as the geometry,stiffness,self-weight,and mechanical model of ***,the interface contact conditions and spatial relations were examined within the context of deep-sea slides and their interactions with *** upon a thorough review of these achievements,future directions were proposed for assessing and characterizing the key factors affecting slide impact loading on pipelines.A comprehensive understanding of these results is essential for the sustainable development of deep-sea pipeline projects associated with seabed resource development and the implementation of disaster prevention measures.

关键词： Deep-sea fluidized slides Pipes Impact forces Shear behavior of slides Interface contact conditions Spatial relation

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Stochastic Analysis and Modeling of Velocity Observations in Turbulent Flows

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Journal of Environmental & Earth Sciences 2024年第1期6卷 45-56页

作者： Evangelos Rozos Jorge Leandro Demetris Koutsoyiannis Institute for Environmental Research&Sustainable Development National Observatory of AthensAthens15236Greece Research Institute for Water and Environment University of SiegenSiegen57076Germany Department of Water Resources and Environmental engineering School of civil engineering National Technical University of AthensAthens15780Greece

Highly turbulent water flows,often encountered near human constructions like bridge piers,spillways,and weirs,display intricate dynamics characterized by the formation of eddies and *** formations,varying in sizes and lifespans,significantly influence the distribution of fluid velocities within the ***,the rapid velocity fluctuations in highly turbulent flows lead to elevated shear and normal stress *** this reason,to meticulously study these dynamics,more often than not,physical modeling is employed for studying the impact of turbulent flows on the stability and longevity of nearby *** the effectiveness of physical modeling,various monitoring challenges arise,including flow disruption,the necessity for concurrent gauging at multiple locations,and the duration of *** these challenges,image velocimetry emerges as an ideal method in fluid mechanics,particularly for studying turbulent *** account for measurement duration,a probabilistic approach utilizing a probability density function(PDF)is suggested to mitigate uncertainty in estimated average and maximum ***,it becomes evident that deriving the PDF is not straightforward for all turbulence-induced *** response,this study proposes a novel approach by combining image velocimetry with a stochastic model to provide a generic yet accurate description of flow dynamics in such *** integration enables an approach based on the probability of failure,facilitating a more comprehensive analysis of turbulent *** an approach is essential for estimating both short-and long-term stresses on hydraulic constructions under assessment.

关键词： Smart modeling Turbulent flows Data analysis Stochastic analysis Image velocimetry

A Stable FE-FD Method for Anisotropic Parabolic PDEs with Moving Interfaces

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Communications on Applied Mathematics and Computation 2024年第2期6卷 992-1012页

作者： Baiying Dong Zhilin Li Juan Ruiz-Alvarez School of civil and hydraulic engineering NingXia UniversityYinchuan 750021NingxiaChina School of Mathematics and Computer Science NingXia Normal UniversityGuyuan 756000NingxiaChina Department of Mathematics North Carolina State UniversityRaleighNC 27695-8205USA Departamento de Matematica Aplicada y Estadistica Universidad Politecnica de CartagenaCartagenaSpain

In this paper,a new finite element and finite difference(FE-FD)method has been developed for anisotropic parabolic interface problems with a known moving interface using Cartesian *** the spatial discretization,the standard P,FE discretization is applied so that the part of the coefficient matrix is symmetric positive definite,while near the interface,the maximum principle preserving immersed interface discretization is *** the time discretization,a modified Crank-Nicolson discretization is employed so that the hybrid FE-FD is stable and second order *** terms are needed when the interface crosses grid *** moving interface is represented by the zero level set of a Lipschitz continuous *** experiments presented in this paper confirm second orderconvergence.

关键词： Anisotropic parabolic interface problem Hybrid finite element and finite difference(FE-FD)discretization Modified Crank Nicolson scheme

Impact of mica on geotechnical behavior of weathered granitic soil using macro and micro investigations

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Journal of Rock Mechanics and Geotechnical engineering 2024年第6期16卷 2250-2266页

作者： Xianwei Zhang Xinyu Liu Haodong Gao Gang Wang Ran An Zhu Liang State Key Laboratory of Geomechanics and Geotechnical engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China School of civil and hydraulic engineering Huazhong University of Science and TechnologyWuhan430074China College of Urban Construction Wuhan University of Science and TechnologyWuhan430065China university of Chinese Academy of Sciences Beijing100049China Guangzhou Urban Planning&Design Survey Research Institute Guangzhou510000China Guangdong Enterprise Key Laboratory for Urban Sensing Monitoring and Early WarningGuangzhou510000China

The micaceous weathered granitic soil(WGS)is frequently encountered in civil engineering worldwide,unfortunately little information is available regarding how mica affects the physico-mechanical behaviors of *** study prepares reconstituted WGS with different mica contents by removing natural mica in theWGS,and then mixes it with commercial mica *** geotechnical behavior as well as the microstructures of the mixtures are *** addition of mica enables the physical indices of WGS to be specific combinations of coarser gradation and high permeability but high Atterberg ***,high mica content in WGS was found to be associated with undesirable mechanical properties,including increased compressibility,disintegration,and swelling potential,as well as poor compactability and low effective frictional *** analysis indicates that the influence of mica on the responses of mixtures originates from the intrinsic nature of mica as well as the particle packing being formed *** exists in the mixture as stacks of plates that form a spongy structure with high compressibility and swelling *** among the plates give the soil high water retention and high Atterberg *** pores are also generated by soil particles with bridging packing,which enhances the permeability and water-soil interactions upon *** study provides a microlevel understanding of how mica dominates the behavior of WGS and provides new insights into the effective stabilization and improvement of micaceous soils.

关键词： Weathered granitic soil(WGS) Mica Microstructure Physical properties Mechanical properties Mechanism

hydraulic fracturing behaviors of shale under coupled stress and temperature conditions simulating different burial depths

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International Journal of Mining Science and Technology 2024年第6期34卷 783-797页

作者： Qin Zhou Zheming Zhu Wei Liu Huijun Lu Zidong Fan Xiaofang Nie Cunbao Li Jun Wang Li Ren MOE Key Laboratory of Deep Earth Science and engineering College of Architecture and EnvironmentSichuan UniversityChengdu 610065China Downhole Operating Company CNPC Chuanqing Drilling and Exploration Engineering Co.Ltd.Shenzhen 518060China School of Architecture and civil engineering Xihua UniversityChengdu 610065China Guangdong Provincial Key Laboratory of Deep Earth Sciences and Geothermal Energy Exploitation and Utilization Shenzhen UniversityShenzhen 518060China

Fracture propagation in shale under in situ conditions is a critical but poorly understood mechanical process in hydraulic fracturing for deep shale gas reservoirs. To address this, hydraulic fracturing experiments were conducted on hollow double-wing crack specimens of the Longmaxi shale under conditions simulating the ground surface(confining pressure σ_(cp)=0, room temperature(Tr)) and at depths of 1600 m(σ_(cp)=40 MPa, Ti=70 ℃) and 3300 m(σ_(cp)=80 MPa, high temperature Ti=110 ℃) in the study *** in situ stress was found to significantly increase fracture toughness through constrained microcracking and particle frictional bridging mechanisms. Increasing the temperature enhances rather than weakens the fracture resistance because it increases the grain debonding length, which dissipates more plastic energy and enlarges grains to close microdefects and generate compressive stress to inhibit microcracking. Interestingly, the fracture toughness anisotropy in the shale was found to be nearly constant across burial depths, despite reported variations with increasing confining pressure. Heated water was not found to be as important as the in situ environment in influencing shale fracture. These findings emphasize the need to test the fracture toughness of deep shales under coupled in situ stress and temperature conditions rather than focusing on either in situ stress or temperature alone.

关键词： hydraulic fracturing Fracture toughness Shale Anisotropy Deep rock mechanics

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Influence of High-Density Bedding Plane Characteristics on hydraulic Fracture Propagation in Shale Oil Reservoir

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Computer Modeling in engineering & Sciences 2024年第9期140卷 3051-3071页

作者： Xiao Yan Di Wang Haitao Yu State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Beijing102206China State Energy Center for Shale Oil Research and Development Beijing102206China Department of Geotechnical engineering College of civil engineering Tongji UniversityShanghai200092China Petroleum Exploration and Production Research Institute SINOPECBeijing102206China Key Laboratory of Deep Earth Science and engineering(Sichuan university) Ministry of EducationChengdu610065China

The existence of high-density bedding planes is a typical characteristic of shale oil *** the behavior of hydraulic fracturing in high-density laminated rocks is significant for promoting shale oil *** this study,a hydraulic fracturing model considering tensile failure and frictional slip of the bedding planes is established within the framework of the unified pipe-interface element method(UP-IEM).The model developed for simulating the interaction between the hydraulic fracture and the bedding plane is validated by comparison with experimental *** hydraulic fracturing patterns in sealed and unsealed bedding planes are ***,the effects of differential stress,bedding plane permeability,spacing,and the friction coefficient of the bedding plane are *** results showed that a single main fracture crossing the bedding planes is more likely to form in sealed bedding planes under high differential *** decrease in bedding plane permeability and the increase in the friction coefficient also promote the fracture propagating perpendicular to the bedding *** with high-density bedding planes has a poorer fracturing effect than that with low-density bedding planes,as the hydraulic fracture is prone to initiate and propagate along the bedding ***,higher injection pressure is needed to maintain fracture propagation along the *** increase in bedding density will lead to a smaller fracturing *** fluid seepage into the bedding planes slows shale *** is recommended that increasing the injection flow rate,selecting alternative fracturing fluids,and employing multi-well/multi-cluster fracturing may be efficient methods to improve energy production in shale oil reservoirs.

关键词： hydraulic fracturing bedding planes shale unified pipe-interface element method

面向地外建造的星壤基材料性能与表征（英文）

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engineering 2024年第6期 159-181页

作者：周诚高玉月周燕佘伟史玉升丁烈云缪昌文 national Center of Technology Innovation for Digital Construction Huazhong University of Science and Technology School of civil and hydraulic engineering Huazhong University of Science and Technology School of Materials Science and engineering Southeast University State Key Laboratory of Materials Processing and Die & Mould Technology School of Materials Science and Engineering Huazhong University of Science and Technology

The construction of extraterrestrial bases has become a new goal in the active exploration of deep *** the construction techniques, in situ resource-based construction is one of the most promising because of its good sustainability and acceptable economic cost, triggering the development of various types of extraterrestrial construction materials. A comprehensive survey and comparison of materials from the perspective of performance was conducted to provide suggestions for material selection and optimization. Thirteen types of typical construction materials are discussed in terms of their reliability and applicability in extreme extraterrestrial environment. Mechanical, thermal and optical, and radiation-shielding properties are considered. The influencing factors and optimization methods for these properties are analyzed. From the perspective of material properties, the existing challenges lie in the comprehensive, long-term, and real characterization of regolith-based construction ***, the suggested future directions include the application of high-throughput characterization methods, accelerated durability tests, and conducting extraterrestrial experiments.

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Retrospective and prospective review of the generalized nonlinear strength theory for geomaterials

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International Journal of Minerals,Metallurgy and Materials 2024年第8期31卷 1767-1787页

作者： Shunchuan Wu Jiaxin Wang Shihuai Zhang Shigui Huang Lei Xia Qianping Zhao Faculty of Land Resource engineering Kunming University of Science and TechnologyKunming 650093China Key Laboratory of Geohazard Forecast and Geoecological Restoration in Plateau Mountainous Area MNRKunming 650093China Yunnan Key Laboratory of Geohazard Forecast and Geoecological Restoration in Plateau Mountainous Area Kunming 650093China School of Earth and Space Sciences University of Science and Technology of ChinaHefei 230026China School of civil and Resource engineering University of Science and Technology BeijingBeijing 100083China

Strength theory is the basic theory for calculating and designing the strength of engineering materials in civil,hydraulic,mechanical,aerospace,military,and other engineering ***,the comprehensive study of the generalized nonlinear strength theory(GNST)of geomaterials has significance for the construction of engineering rock *** paper reviews the GNST of geomaterials to demonstrate the research status of nonlinear strength characteristics of geomaterials under complex stress ***,it systematically summarizes the research progress of GNST(classical and empirical criteria).Then,the latest research the authors conducted over the past five years on the GNST is introduced,and a generalized three-dimensional(3D)nonlinear Hoek‒Brown(HB)criterion(NGHB criterion)is proposed for practical *** criterion can be degenerated into the existing three modified HB criteria and has a better prediction *** strength prediction errors for six rocks and two in-situ rock masses are 2.0724%-3.5091%and 1.0144%-3.2321%,***,the development and outlook of the GNST are expounded,and a new topic about the building strength index of rock mass and determining the strength of in-situ engineering rock mass is *** summarization of the GNST provides theoretical traceability and optimization for constructing in-situ engineering rock mass strength.

关键词： rock mechanics rock mass strength strength theory failure criterion Hoek-Brown criterion intermediate principal stress deviatoric plane smoothness and convexity

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