A new iterative order reduction (IOR) method for eigensolutions of large structures

Order reduction is a computationally efficient method to estimate some lowest eigenvalues and the corresponding eigenvectors of large structural systems by reducing the order of the original model to a smaller one. But its accuracy is limited to a small range of frequencies that depends on the selection of the retained degrees of freedom. This paper proposes a new iterative order reduction (IOR) technique to obtain accurately the eigensolutions of large structural systems. The technique retains all the inertia terms associated with the removed degrees of freedom. This hence leads to the reduced mass matrix being in an iterated form and the reduced stiffness matrix constant. From these mass and stiffness matrices, the eigensolutions of the reduced system can be obtained iteratively. On convergence the reduced system reproduces the eigensolutions of the original structure. A proof of the convergence property is also presented. Applications of the method to a practical GARTEUR structure as well as a plate have demonstrated that the proposed method is comparable to the commonly used Subspace Iteration method in terms of numerical accuracy. Moreover, it has been found that the proposed method is computationally more efficient than the Subspace Iteration method. Copyright © 2003 John Wiley & Sons, Ltd.     

综述老油田改善开发效果及提高采收率技术

中国陆上老油田已进入高含水后期开发，随着开采程度加深，地下油水关系越来越复杂，剩余油分散，给油田稳产和调整挖潜带来的难度越来越大。但目前老油田储量和产量的比例，仍占陆上总开发储量和产量的７０％以上，是生产上的主力，其潜力也最大，仍然是今后调整挖潜的主要对象。鉴于中国陆上油田绝大多数为陆相储层，构造复杂，非均质严重，原油粘度偏高，石油地质特点决定了水驱油的不均匀性及剩余油分布的复杂性，潜力就存在于这种复杂之中。根据中国陆上石油地质特点和老油田开发现状，围绕改善开发效果及提高采收率着重阐述了四个方面的配套技术：即认识油藏的配套技术，主要包括油藏动态监测技术、油藏精细描述技术、油藏数值模拟技术；完善注水开发配套技术，主要包括注水结构调整、产液结构及含水结构调整、钻取高效调整井、改造“双低”单元、配套工艺技术等；热力采油配套技术；化学驱采油配套技术。经过多年来的努力，我国陆上油田提高采收率技术有了明显进步，针对不同类型油藏潜力分布特点，采用各种有效方法及其配套技术，为挖潜增储、增产提供了很大的余地。     

纳米硅胶体系驱油理论与数学建模

为了定量研究纳米级二氧化硅粉体成胶体系的驱油效果, 对纳米硅胶驱油机理进行了理论分析。在连续性介质渗流理论、硅胶溶液流变性理论、硅胶在孔隙介质内吸附和运移理论基础上, 建立了一个两相多组分硅胶驱油数学模型, 并开发了一个数值模拟器, 定量模拟了硅胶质量浓度、注入体积和注入方式对孔、渗参数和开发效果的影响。结果表明, 纳米硅胶溶液驱油会降低储集层孔、渗参数, 但是会大幅度提高采收率; 段塞注入优于交替和连续驱油方式。     

高温高矿化度CO2泡沫性能实验研究

在高温、高矿化度条件下,通过测试起泡剂浓度、温度、矿化度和压力对CO₂泡沫性能的影响,筛选出了耐温、耐盐性能良好的表面活性剂作为起泡剂,并通过动态驱替实验,考察了起泡剂在高温、高矿化度条件下的CO₂泡沫的流度控制和封堵能力。实验结果表明,HLB值在14¹6之间的两性和非离子表面活性剂复配的起泡剂泡沫稳定性较好;高压下（15MPa）所产生CO₂泡沫更为稳定,在100℃下驱替实验所测得最大阻力因子达130,表现出良好的封堵和流度控制性能。泡沫仪测试和驱替实验结果对比表明,泡沫半衰期对阻力因子的影响更为敏感,是衡量泡沫稳定性和封堵能力的主要因素。表4图5参11     

综述老油田改善开发效果及提高采收率技术

中国陆上老油田已进入高含水后期开发,随着开采程度加深,地下油水关系越来越复杂,剩余油分散,给油田稳产和调整挖潜带来的难度越来越大.但目前老油田储量和产量的比例,仍占陆上总开发储量和产量的70%以上,是生产上的主力,其潜力也最大,仍然是今后调整挖潜的主要对象.鉴于中国陆上油田绝大多数为陆相储层,构造复杂,非均质严重,原油粘度偏高,石油地质特点决定了水驱油的不均匀性及剩余油分布的复杂性,潜力就存在于这种复杂之中.根据中国陆上石油地质特点和老油田开发现状,围绕改善开发效果及提高采收率着重阐述了四个方面的配套技术:即认识油藏的配套技术,主要包括油藏动态监测技术、油藏精细描述技术、油藏数值模拟技术;完善注水开发配套技术,主要包括注水结构调整、产液结构及含水结构调整、钻取高效调整井、改造“双低”单元、配套工艺技术等;热力采油配套技术;化学驱采油配套技术.经过多年来的努力,我国陆上油田提高采收率技术有了明显进步,针对不同类型油藏潜力分布特点,采用各种有效方法及其配套技术,为挖潜增储、增产提供了很大的余地.     

Evaluation of the EOR Potential in Hydraulically Fractured Shale Oil Reservoirs by Cyclic Gas Injection

Gas flooding in fractured reservoirs may not be an effective avenue for improving oil recovery because the injected fluids could break-through to production wells via the fracture network. A cyclic injection scheme is one way to solve this problem. In this study, the authors propose to use cyclic gas injection to improve hydraulically fractured shale oil recovery. They used a simulation approach to evaluate the enhanced oil recovery (EOR) potential from cyclic gas injection. The simulation results indicate that total oil recovery can be increased up to 29% by cyclic gas injection, compared with the 6.5% recovery from the primary depletion. If a higher pressure is used to reach fully miscibility with reservoir oil and more cycles are employed, more oil recovery is expected.     

无线CORBA中间件的系统结构分析与研究

随着无线技术的快速发展,移动网络中的分布式计算也日趋重要。无线CORBA针对解决无线接入和终端移动这两个关键问题,系统地展现、归纳和评述了无线CORBA的总体系统结构、原理与规范,分析了移动IOR、GIOP隧道协议和越区切换管理等无线CORBA中间件体系的核心支撑技术,给出了实现终端GTP通信处理的系统级设计解决方案,指出了存在的问题和进一步的研究方向。这些工作对移动分布式系统的研究和实践具有一定的参考价值。     

Recreational use of cocaine eliminates inhibition of return.

Chronic and recreational use of cocaine has been shown to impair inhibitory output control (response inhibition) but whether input control is also affected is an open question. For the first time, this study compared the ability to perform a cued target-discrimination task that measured inhibition of return (IOR), a reflexive inhibitory mechanism that delays attention from returning to a previously attended location, in adult recreational users and in a cocaine-free-matched sample controlled for age, race, gender distribution, and level of intelligence. Results show that the recreational use of cocaine eliminates IOR, suggesting that input control is strongly impaired. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Low‐temperature carrier dyeing of poly(vinyl chloride) fibers with disperse dyes

The effects of various carriers on the color yield of poly(vinyl chloride) (PVC) filaments in a disperse dyeing system were investigated. The dyeability of disperse dyes on PVC fiber was improved using appropriate carriers. The enhancement of dye uptake imparted by carriers coincided with the reduction in glass‐transition temperature, which in turn coincided approximately with the similarity of the inorganic/organic ratio values between PVC fibers and carriers. The results clearly demonstrate that hydrophobic carriers function as diluents of PVC fiber, facilitating dye diffusion by increasing segmental mobility of the fiber. The dyed PVC filaments with disperse dyes showed reasonable levels of build‐up and color fastness properties in the carrier‐assisted dyeing. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3896–3904, 2003     

Comparison of numerical codes for coupled thermo-hydro-mechanical simulations of fractured media

Geo-energy and geo-engineering applications,such as improved oil recovery(IOR),geologic carbon storage,and enhanced geothermal systems(EGSs),involve coupled thermo-hydro-mechanical(THM)processes that result from fluid injection and production.In some cases,reservoirs are highly fractured and the geomechanical response is controlled by fractures.Therefore,fractures should explicitly be included into numerical models to realistically simulate the THM responses of the subsurface.In this study,we perform coupled THM numerical simulations of water injection into naturally fractured reservoirs(NFRs) using CODE_BRIGHT and TOUGH-UDEC codes.CODE_BRIGHT is a finite element method(FEM) code that performs fully coupled THM analysis in geological media and TOUGH-UDEC sequentially solves coupled THM processes by combining a finite volume method(FVM) code that solves nonisothermal multiphase flow(TOUGH2) with a distinct element method(DEM) code that solves the mechanical problem(UDEC).First,we validate the two codes against a semi-analytical solution for water injection into a single deformable fracture considering variable permeability based on the cubic law.Then,we compare simulation results of the two codes in an idealized conceptual model that includes one horizontal fracture and in a more realistic model with multiple fractures.Each code models fractures differently.UDEC calculates fracture deformation from the fracture normal and shear stiffnesses,while CODE_BRIGHT treats fractures as equivalent porous media and uses the equivalent Young's modulus and Poisson's ratio of the fracture.Finally,we obtain comparable results of pressure,temperature,stress and displacement distributions and evolutions for the single horizontal fracture model.Despite some similarities,the two codes provide increasingly different results as model complexity increases.These differences highlight the challe nging task of accurately modeling coupled THM processes in fractured media given their high nonlinearity.