Permeability Estimation with the Augmented Lagrangian Method for a Nonlinear Diffusion Equation     

Trygve K. Nilssen  Trond Mannseth  Xue-Cheng Tai 《Computational Geosciences》2003,7(1):27-47

We consider numerical identification of the piecewise constant permeability function in a nonlinear parabolic equation, with the augmented Lagrangian method. By studying this problem, we aim at also gaining some insight into the potential ability of the augmented Lagrangian method to handle permeability estimation within the full two-phase porous-media flow setting. The identification is formulated as a constrained minimization problem. The parameter estimation problem is reduced to a coupled nonlinear algebraic system, which can be solved efficiently with the conjugate gradient method. The methodology is developed and numerical experiments with the proposed method are presented.  相似文献   

采用交换式路由器结合代理服务器作为互联网接入方案的剖析     

詹利群 《气象研究与应用》2003,24(4):56-58

介绍交换式路由器结合代理服务器在实现不同网段局域网共享接入国际互联网的具体应用。  相似文献   

921型超低频有源伺服式速度,位移计   总被引：1，自引：2，他引：1  

杨学山  黄浩华 《地震工程与工程振动》1997,17(3):117-123

本介绍一种在很小体积的往复式摆上采用有源伺服技术实现超低频大幅值测量用的速度计、位移计，它可在多个频带测量速度和位移。最低频率可达０．０４Ｈｚ，最大可测位移为±１５ｍ。它可用于海浪浪高、抽油机行程、高柔结构的超低频大位移测量。该仪器于１９９２年获得国家专利，并获得中国专利博览会银奖。  相似文献   

Inferring the relative measure of principal stress components     

Peiliang Xu  Seiichi Shimada 《Geophysical Journal International》1997,130(1):F1-F4

The phase velocity and the attenuation coefficient of compressional seismic waves, propagating in poroelastic, fluid-saturated, laminated sediments, are computed analytically from first principles. The wavefield is found to be strongly affected by the medium heterogeneity. Impedance fluctuations lead to poroelastic scattering; variations of the layer compressibilities cause inter-layer flow (a 1-D macroscopic local flow). These effects result in significant attenuation and dispersion of the seismic wavefield, even in the surface seismic frequency range, 10–100 Hz. The various attenuation mechanisms are found to be approximately additive, dominated by inter-layer flow at very low frequencies. Elastic scattering is important over a broad frequency range from seismic to sonic frequencies. Biot's global flow (the relative displacement of solid frame and fluid) contributes mainly in the range of ultrasonic frequencies. From the seismic frequency range up to ultrasonic frequencies, attenuation due to heterogeneity is strongly enhanced compared to homogeneous Biot models. Simple analytical expressions for the P -wave phase velocity and attenuation coefficient are presented as functions of frequency and of statistical medium parameters (correlation lengths, variances). These results automatically include different asymptotic approximations, such as poroelastic Backus averaging in the quasi-static and the no-flow limits, geometrical optics, and intermediate frequency ranges.  相似文献   

Hot fluid migration in compressible saturated porous media     

Maurizio Bonafede  Mariangela Mazzanti 《Geophysical Journal International》1997,128(2):383-398

  相似文献   

泡沫泥浆钻进工艺及护壁堵漏机理研究          下载免费PDF全文

朱宗培  费立  陈礼仪  吴飞 《探矿工程》1996,(5):34-36

介绍了所研制的ＤＦ－１型泡沫剂组分及性能；对泡沫泥浆钻进的配方进行了研究，得出的最优配方应用于现场，取得了较好的效果，并对泡沫泥浆的护壁机理进行了研究。  相似文献   

Application of an optimum design technique for determining the coefficient of consolidation by using piezocone test data   总被引：4，自引：0，他引：4  

Y.S. Kim  S.R. Lee  Y.T. Kim 《Computers and Geotechnics》1997,21(4):885-293

For normally consolidated clay, several researchers have developed a number of theoretical time factors to determine the coefficient of consolidation from piezocone test results. However, depending on assumptions and analytical techniques, it could vary considerably, even for a specific degree of consolidation. In this paper a method is proposed to determine a consistent coefficient of consolidation by applying the concept of an optimum design technique over all ranges of the degree of consolidation. Initial excess pore pressure distribution is assumed to be capable of being obtained by the successive spherical cavity expansion theory. The dissipation of pore pressure is simulated by means of a two-dimensional linear-uncoupled axi-symmetric consolidation analysis. The minimization of differences between measured and predicted excess pore pressure was carried out by the BFGS unconstrained optimum design algorithm with a one-dimensional golden section search technique. By analyzing numerical examples and in-situ test results, it was found that the adopted optimum design technique gives consistent and convergent results.  相似文献   

Flexible spectral methods for the generation of random fields with power-law semivariograms     

Johannes Bruining  Diederik van Batenburg  Larry W. Lake  An Ping Yang 《Mathematical Geology》1997,29(6):823-848

Random field generators serve as a tool to model heterogeneous media for applications in hydrocarbon recovery and groundwater flow. Random fields with a power-law variogram structure, also termed fractional Brownian motion (fBm) fields, are of interest to study scale dependent heterogeneity effects on one-phase and two-phase flow. We show that such fields generated by the spectral method and the Inverse Fast Fourier Transform (IFFT) have an incorrect variogram structure and variance. To illustrate this we derive the prefactor of the fBm spectral density function, which is required to generate the fBm fields. We propose a new method to generate fBm fields that introduces weighting functions into the spectral method. It leads to a flexible and efficient algorithm. The flexibility permits an optimal choice of summation points (that is points in frequency space at which the weighting function is calculated) specific for the autocovariance structure of the field. As an illustration of the method, comparisons between estimated and expected statistics of fields with an exponential variogram and of fBm fields are presented. For power-law semivariograms, the proposed spectral method with a cylindrical distribution of the summation points gives optimal results.  相似文献   

秦家屯油田储层的敏感性评价   总被引：1，自引：0，他引：1  

李永刚 《吉林大学学报(地球科学版)》2004,(Z1)

储层的敏感性评价是研究储层损害机理、保护储层或减小储层损害的依据,是搞好油田注水开发的基础。采用岩心流动实验装置,开展了储层敏感性的室内实验。结果表明秦家屯油田储集层对流体速度表现为弱敏感性,对盐敏表现为中等偏弱盐敏性,对酸表现为无敏感性,随着注水速度的增加,岩心的渗透率也随之增大,并未出现“桥堵”和“卡堵”现象,说明储层中不稳定的固相颗粒含量低,不能堵塞地层,油层增产可采用提高注入速度、酸化等措施,油层水敏为中等偏弱到中等偏强,注水前要注入稳定剂。碱敏表现为弱碱敏或中等碱敏,对该区三次采油作业中,尤其是碱水驱油要特别注意。  相似文献   

渤南油田中部古近系沙河街组低渗透储层岩石学和成岩作用   总被引：2，自引：0，他引：2       下载免费PDF全文

李海燕  彭仕宓  黄述旺 《沉积与特提斯地质》2004,24(1):84-90

该区储层岩石类型主要为岩屑质长石砂岩，溶解作用是主要的建设性成岩作用，压实、自生矿物充填和胶结作用是主要的破坏性成岩作用，成岩阶段处于晚成岩A亚期。该区储层较高的孔隙度是晚成岩期强烈的溶解作用形成次生溶孔的结果，而储层砂岩较低渗透率的主要成因机理是成岩期各种自生矿物的充填和胶结作用；此外，溶蚀作用形成的孤立、互不连通的粒间孔也是形成低渗微细喉道储层的主要原因。有利孔隙组合为粒间溶蚀孔-原生粒间孔-粒内破碎缝，有利储层的分布受砂体分布、构造配置及成岩作用的联合控制。  相似文献