Modeling 3D thermal fracture propagation by transient cooling using virtual multidimensional internal bonds          下载免费PDF全文

K. Huang  A. Ghassemi 《国际地质力学数值与分析法杂志》2016,40(17):2293-2311

Thermal fracturing can play an important role in development of unconventional petroleum and geothermal resources. Thermal fractures can result from the nonlinear deformation of the rock in response to thermal stress related to cold water injection as well as heating. Before the rock reaches the final failure stage, material softening and bulk modulus degradation can cause changes in the thermo‐mechanical properties of the solid. In order to capture this aspect of the rock fracture, a virtual multidimensional internal bond‐based thermo‐mechanical model is derived to track elastic, softening, and the failure stages of the rock in response to the temporal changes of its temperature field. The variations in thermo‐mechanical properties of the rock are derived from a nonlinear constitutive model. To represent the thermo‐mechanical behavior of pre‐existing fractures, the element partition method is employed. Using the model, numerical simulation of 3D thermal fracture propagation in brittle rock is carried out. Results of numerical simulations provide evidence of model verification and illustrate nonlinear thermal response and fracture development in rock under uniform cooling. In addition, fracture coalescence in a cluster of fractures under thermal stress is illustrated, and the process of thermal fracturing from a wellbore is captured. Results underscore the importance of thermal stress in reservoir stimulation and show the effectiveness of the model to predict 3D thermal fracturing. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Modeling three‐dimensional hydraulic fracture propagation using virtual multidimensional internal bonds     

K. Huang  Z. Zhang  Ahmad Ghassemi 《国际地质力学数值与分析法杂志》2013,37(13):2021-2038

Propagation of fractures, especially those emanating from wellbores and closed natural fractures, often involves Mode I and Mode II, and at times Mode III, posing significant challenges to its numerical simulation. When an embedded inclined fracture is subjected to compression, the fracture edge is constrained by the surrounding materials so that its true propagation pattern cannot be simulated by 2D models. In this article, a virtual multidimensional internal bond (VMIB) model is presented to simulate three‐dimensional (3D) fracture propagation. The VMIB model bridges the processes of macro fracture and micro bond rupture. The macro 3D constitutive relation in VMIB is derived from the 1D bond in the micro scale and is implemented in a 3D finite element method. To represent the contact and friction between fracture surfaces, a 3D element partition method is employed. The model is applied to simulate fracture propagation and coalescence in typical laboratory experiments and is used to analyze the propagation of an embedded fracture. Simulation results for single and multiple fractures illustrate 3D features of the tensile and compressive fracture propagation, especially the propagation of a Mode III fracture. The results match well with the experimental observation, suggesting that the presented method can capture the main features of 3D fracture propagation and coalescence. Moreover, by developing an algorithm for applying pressure on the fracture surfaces, propagation of a natural fracture is also simulated. The result illustrates an interesting and important phenomenon of Mode III fracture propagation, namely the fracture front segmentation. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Internal erosion of chemically reinforced granular materials: a mathematical modeling approach     

Tony Khalil  Nadia Saiyouri  Bogdan Muresan  Pierre‐Yves Hicher 《国际地质力学数值与分析法杂志》2013,37(5):491-502

Internal erosion (IE) affects the stability of natural and reinforced materials by causing instability within their granular structure. The dislodgement and transport of eroded particles affect both the particulate concentration of eroding fluid and the pore network of eroded material. In this study, we examined these modifications using a transport model with a finite element code. First, IE tests on chemically reinforced sand columns were performed to obtain information about eroded material loss of mass, particulate concentration of effluent, porosity and permeability modifications, and existing IE stages. Second, based on experimental results, a mathematical one‐dimensional model has been formulated to monitor the evolution and spatial distribution of erodible solids, fluidized particles, porosity, permeability, and seepage stresses. The model consists of a set of coupled nonlinear differential equations solved in sequence. It provides valuable information about the extent and the dynamics of structural changes, which can be used to estimate an IE time for the hydraulic work to reach failure. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Topographic instability and multiple equilibria on an f-plane     

P. F. Linden 《地球物理与天体物理流体动力学》2013,107(3-4):163-182

Abstract

The flow of a two-layer flow in a rotating channel on an f-plane over topography with sinusoidal variation of height in a direction parallel to the flow is investigated. When the two layers flow in opposite directions a resonance is found when the topographic scale matches the free mode of the system. We examine the stability of the forced mode in the vicinity of this resonance by means of a perturbation expansion of the topographic height. Both subresonant and super-resonant instabilities are found and their equilibration is examined. For small values of the dissipation multiple equilibria are found. The topographic drag releases potential energy even when the flow is baroclinically stable.  相似文献   

On induction effects at EISCAT and IMAGE magnetometer stations     

Ari Viljanen  Kirsti Kauristie  Kari Pajunpää 《Geophysical Journal International》1995,121(3):893-906

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遥测地震台网实时处理系统          下载免费PDF全文

刘凤祥 《地震工程学报》1994,16(3):73-77

本文介绍了采用程序驻留内存技术，利用系统的硬件中断和时钟中断，在微机上研制成功了实时处理系统。该系统具有前后台处理功能，能够在主机ＣＰＵ中同时运行多道程序，使数据采集、事件检测、数据转存、地震定位等均能进行实时处理。该系统可用于区域遥测地震台网和地方遥测地震台网的实时处理。  相似文献   

陆地卫星五号TM图像系统纠正产品的几何精度分析     

王新民  章蕾 《遥感学报》1989,(4)

为了鉴定陆地卫星5号系统纠正TM图像产品的精度,我们以1:5万地形图为基准,对四景TM图像作了精度分析。结果表明,系统纠正后的TM图像产品,内部几何精度相当好,有较小的旋转、比例误差。采用一阶多项式即可建立TM图像和地形图之间的几何关系,其误差为1个像元左右。TM图像的大地绝对误差,可通过将整个TM图像沿x,y方向平移的方法来加以校正。  相似文献   

Geographic variations in shell growth rates of the mussel Diplodon chilensis from temperate lakes of Chile: Implications for biodiversity conservation     

Claudio Valdovinos  Pablo Pedreros 《Limnologica》2007,37(1):63-75

The Chilean lake district includes diverse lentic ecosystems along ca. 700 km of the country (36°–43°S), including the “Nahuelbutan lakes”, “Araucanian lakes” and “Chiloe lakes”. This area is recognized as an important “hot spot” of benthic freshwater biodiversity in Southern South America. In Chilean temperate lakes, increased nutrient loads of P and N caused eutrophication, particularly in the Nahuelbutan Lakes. The freshwater Hyriidae mussel Diplodon chilensis (Gray, 1828) which is one of the most abundant species in Chilean temperate lakes, is known to be very susceptible to eutrophication. This species presents a clear reduction in its geographic ranges and is considered to be a threatened species in many Chilean lakes. In this study, we used a correlative approach to determine how eutrophication-driven changes in the food supply and in geographical parameters of different Chilean lakes affected the shell growth rates of D. chilensis. The results obtained from sclerochronological analyses of the mussel shells suggest an association with a group of environmental variables, including geographical types (negative), such as latitude and altitude, and limnological types (positive), especially phosphorous and turbidity. However, the D. chilensis populations under extreme conditions of turbidity in eutrophic and hypertrophic lakes are extinct or nearly so. The high positive correlation of the mean D. chilensis growth rates with orthophosphate (R=0.76; P<0.05), in relation to dissolved inorganic nitrogen, suggests that P is the major limiting factor of the primary productivity in Chilean temperate lakes. We discuss some implications of our results in terms of the conservation of biodiversity in temperate lake ecosystems at different taxonomic levels.  相似文献   

非饱和土的有效应力与抗剪强度   总被引：1，自引：1，他引：1  

王志玲  张印杰  丰土根 《岩土力学》2002,23(4):432-436

从孔隙土的存在状态出发，探讨了吸力的两种不同作用效果与非饱和形态的关系，从理论上论证了Bishop公式的正确性澄清了多年来一个基本概念上的误解。用新的观点阐述了非饱和土中抗剪强度分布不均匀及浸水湿陷的原因；同时还对Fredlund和卢肇钧提出的抗剪强度理论及参数的测试方法进行了分析，提出了各种抗剪强度理论在理论上都是相同的，其区别仅在于确定由吸力产生的那部分有效应力时采用的参数和测试 方法不同。为今后非饱和土的抗剪强度研究从理论转向实用提供了理论基础。  相似文献   

粘弹性介质中的地震波   总被引：1，自引：0，他引：1  

范家参 《地震研究》2001,24(4):358-362

给出了三元件的标准线性粘弹性固体在半平面内传播的地震波的解析解，它是由已知的弹性半平面内的解析解迭粘滞性解而得，从而克服了视地壳为二元件粘弹性体的Voigt模型或Maxell模型的缺点。  相似文献