TTI介质的相速度研究

推导了二维TTI介质的相速度表达式,并且依据推导出来的相速度表达式,模拟并分析了二维TTI介质相速度的传播快照以及TI介质相速度的传播快照;对比并分析了TTI介质和TI介质模型的相速度理论计算值的X分量特征的差异。TTI介质的相速度研究具有较高的理论研究价值和实际应用价值．     

Comparison of Galerkin-type discretization techniques for two-phase flow in heterogeneous porous media

A comparison of Standard Galerkin, Petrov-Galerkin, and Fully-Upwind Galerkin methods for the simulation of two-phase flow in heterogeneous porous media is presented. On the basis of the coupled pressure-saturation equations, a generalized formulation for all three finite element methods is derived and analysed. For flow in homogeneous media, the Petrov-Galerkin method gives excellent results. But this method fails miserably for problems with heterogeneous media. This is because it is not able to capture correctly processes that take place at interfaces when, for instance, the capillary pressure-saturation relationship after Brooks and Corey is assumed. The Fully-Upwind Galerkin method is superior to the Petrov-Galerkin approach because it is able to give correct results for flow in homogeneous and heterogeneous media for the two models of van Genuchten and Brooks-Corey. The widely used formulation which is correct for the homogeneous case cannot be used for heterogeneous media. Instead the straightforward approach of gradp_c in combination with a chord-slope technique must be utilized.     

Sediment transport patterns at Trafalgar offshore windfarm

A simple analytical model of wave propagation has been developed in order to study the potential sediment transport patterns due to the action of currents and waves in the neighborhood of cylindrical structures as well inside a group of these structures. The attention is focused on the study of Trafalgar offshore windfarm, a case in which it has been necessary to analyze the flow trough porous structures in order to model fish growing-cages planned to be installed at each aerogenerator structure. The results are obtained by averaging over one period of wave in order to evaluate the net potential sediment transport. The analysis of the results reveals how the processes of wave diffraction and reflection give rise to periodic patterns of sediment transport around and between the structures.     

Space,time, and situational awareness in natural hazards: a case study of Hurricane Sandy with social media data

ABSTRACT

Various methods have been developed to investigate the geospatial information, temporal component, and message content in disaster-related social media data to enrich human-centric information for situational awareness. However, few studies have simultaneously analyzed these three dimensions (i.e. space, time, and content). With an attempt to bring a space–time perspective into situational awareness, this study develops a novel approach to integrate space, time, and content dimensions in social media data and enable a space–time analysis of detailed social responses to a natural disaster. Using Markov transition probability matrix and location quotient, we analyzed the Hurricane Sandy tweets in New York City and explored how people’s conversational topics changed across space and over time. Our approach offers potential to facilitate efficient policy/decision-making and rapid response in mitigations of damages caused by natural disasters.     

Non-equilibrium interphase heat and mass transfer during two-phase flow in porous media—Theoretical considerations and modeling

Mass and heat transfer occurring across phase-interfaces in multi-phase flow in porous media are mostly approximated using equilibrium relationships or empirical kinetic models. However, when the characteristic time of flow is smaller than that of mass or heat transfer, non-equilibrium situations may arise. Commonly, empirical approaches are used in such cases. There are only few works in the literature that use physically-based models for these transfer terms. In fact, one would expect physical approaches to modeling kinetic interphase mass and heat transfer to contain the interfacial area between the phases as a variable. Recently, a two-phase flow and solute transport model was developed that included interfacial area as a state variable [36]. In that model, interphase mass transfer was modeled as a kinetic process.     

Nuclear Waste Disposal Simulations: Couplex Test Cases

We give some results obtained for the Couplex test cases proposed by the ANDRA. In this paper our aim is twofold. Firstly, to compute the release of nuclides out of the repository by concentrating on the 3D near field (Couplex 2). The simulation of the transport phenomena takes into account the dissolution of the glass containers and congruent emissions of the radio-nuclides including filiation chains and some simplified chemistry. Secondly, it is to use the near field computations in order to simulate the nuclide migrations in a 2D far field (Couplex 3). Coupling in between the two simulations takes into consideration the periodicity of the disposal modules and the geometry of the repository described in Couplex 1. The mixed finite element and discontinuous Galerkin methods are used to solve the convection–diffusion equations. In order to handle the nonlinear precipitation/dissolution term, we developed a new iterative technique that combines Picard and Newton–Raphson methods.     

Numerical simulation of damage–Permeability relationship in brittle geomaterials

Finding a coupling model between a hydraulic parameter such as permeability and a mechanical parameter such as damage is the key element for several recent engineering problems. A review of the technical literature reveals that several mechanical constitutive laws exist which allow determining a damage tensor for a damageable porous material under loading. But the present work develops a method to deduce the permeability change due to the damage propagation.     

油气双相介质理论在辽西凹陷南部岩性圈闭中的应用

辽河西部凹陷是辽河拗陷主要的生油凹陷.随着勘探程度的提高,勘探难度不断增大,近年来对辽西凹陷鸳鸯沟和清水洼陷坡折带以下的岩性油气藏勘探需求日益旺盛.通过双相介质油气勘探方法,利用小波变化时频分析特性,提取地震波能量和频率成分,对工作区内探井频谱特征进行了样本学习,总结出了区内高产井和无油井的频谱特征,预测出勘探风险区域的油气富集程度,再结合地球物理反演技术,明确了下一步岩性圈闭的勘探潜力区域,以降低勘探风险.