共查询到20条相似文献,搜索用时 31 毫秒
1.
以Warren-Root模型为基础,引入分形参数和压缩系数,考虑了压力对具有分形特征的渗透率和孔隙度的影响,验证了变形双重介质分形油藏非线性渗流数学模型.利用离散泛函分析方法,引入不动点原理,就该模型一般形式的差分方程探讨了其解的存在性.研究认为:分形几何理论及方法在正确认识复杂非均质油藏及应力敏感地层油气藏方面具有独到优势. 相似文献
2.
分形复合封闭油藏的试井模型解 总被引:2,自引:0,他引:2
从分形复合储层的物理模型出发,对于内区和外区分别引进了分形维数及分形渗流网络连通状况的分形指数;建立了外边界封闭且考虑井筒储存和表皮效应下的变流率问题的试井分析数学模型;利用Laplace变换法,求得了无因次储层压力和井底压力的Laplace空间解,归纳出的通用公式简化了相应的分析软件设计。 相似文献
3.
A theoretical formulation was developed to express permeability as a function of different fractal dimensions and other scales for porous media . The effective fractal void ratio, the spectral dimension and the fractal dimension of particle mass distribution were introduced. The permeabilities for different soils in China are calculated. The predicted permeability for rice soil was compared with the measured data available in literature. 相似文献
4.
目的 研究在温度和孔隙水压力作用下,各向同性多孔介质材料孔隙度和损伤变量以及分形维数之间的理论关系.方法 基于Mori-Tanaka理论,建立了各向同性多孔介质材料的宏观损伤变量与细观孔隙度之间的联系,利用分形理论推导了各向同性多孔介质材料孔隙度和分形维数之间的关系式.结果 若已知初始时刻的孔隙度、温度和孔隙水压力等的变化情况,就可以求出各向同性多孔介质材料的损伤演化规律,以及孔隙度与分形维数之间的定量关系.结论 文中建立的在温度和孔隙水压力作用下,各向同性多孔介质材料的损伤演化规律以及孔隙度和分形维数之间的定量关系,对于多孔介质材料力学性质的研究具有重要的理论价值. 相似文献
5.
KIM Tongbeum 《中国科学E辑(英文版)》2009,52(6):1688-1697
The solidification behavior of two-phase heterogeneous materials such as close-celled aluminum foams was analytically studied.
The proposed analytical model can precisely predict the location of solidification front as well as the full solidification
time for a two-phase heterogeneous material composed of aluminum melt and non-conducting air pores. Experiments using distilled
water simulating the aluminum melt to be solidified (frozen) were subsequently conducted to validate the analytical model
for two selected porosities (ɛ), ɛ=0 and 0.5. Full numerical simulations with the method of finite difference were also performed to examine the influence of
pore shape on solidification. The remarkable agreement between theory and experiment suggests that the delay of solidification
in the two-phase heterogeneous material is mainly caused by the reduction of bulk thermal conductivity due to the presence
of pores, as this is the sole mechanism accounted for by the analytical model for solidification in a porous medium.
Supported by the National Basic Research Program of China (“973” Project) (Grant Nos. 2006CB601202, 2006CB601203), the National
Natural Science Foundation of China (Grant Nos. 10572111, 10632060), the National 111 Project of China (Grant No. B06024)
and the National High-Tech Research and Development Program of China (“863” Project) (Grant No. 2006AA03Z519). 相似文献
6.
薄层底水油藏部分打开直井试井解释方法研究 总被引:2,自引:0,他引:2
底水油藏在我国较为常见,建立了薄层底水油藏瞬时点源扩散方程,利用Lord Kelvin点源解、叠加原理、镜像反应等获得了该类油藏渗流微分方程的基本解,利用Poisson叠加公式简化表达式,结合点源函数的思想求解了薄层底水油藏直井压力响应函数,计算得到了无因次压力和压力导数双对数理论图版,并在此基础上分析了薄层底水油藏直井渗流特征及其影响因素,编制了试井解释软件. 相似文献
7.
The methods of homogenization and finite elements are employed to predict the effective elastic constants and stress-strain
responses of a new type of lattice structure, the X-structure proposed by the authors in a companion paper. It is shown that
in most cases the predictions by the equivalent homogenization theory agree well with the experimental and 3-dimensional finite
element calculated results. The theoretical and numerical study supports the argument that the X-structure is superior to
the pyramid lattice structure in terms of mechanical strength.
Supported by the National Basic Research Program of China (“973” Project) (Grant No. 2006CB601202), the National Natural Science
Foundation of China (Grant Nos. 10632060, 10825210), the National “111” Project of China (Grant No. B06024) and the National
High-Tech Research and Development Program of China (“863” Project) (Grant No. 2006AA03Z519) 相似文献
8.
具有分形特性的油藏渗流理论进展概述 总被引:3,自引:0,他引:3
近年来,由国外科学家在上世纪80年代创立的分形几何在诸多学科中已得到广泛应用.而今非线性分形理论逐渐被应用于油藏数值模拟中.国外科学家和油藏工程师最先在渗流力学中引入分形维数和分形指数来描述多孔介质及其孔缝的分形特征,打破了采用均质或拟均质假设处理方法近似反应裂缝型多孔介质性质的传统方法,进而产生了应用分形特性描述油藏的分形特征和非均质性的分形油藏理论.应用分形理论建立的油藏数值模型与经典模型相比,虽然分形油藏渗流模型较为复杂,但更能贴近自然、真实的油藏,能够更有效地反映实际油藏的复杂性. 相似文献
9.
An Si/O patterned shell array was fabricated by a technique utilizing nanosphere self assembly and reactive pressure pulsed
laser deposition. The nanostructure produced by this technique enhanced the luminescence intensity by a factor of three compared
with that of a flat film. The amount of enhancement observed coincided well with the expected enhancement by simulation. The
technique in this paper provided a flexible, designable and compatible approach to luminescence enhancement.
Supported by the National Basic Research Program of China (“973” Project) (Grant No. 2002CB613505) and the National Nature
Science Foundation of China (Grant No. 90206046) 相似文献
10.
In remote sensing applications, accurate extraction of land type area after classification is very important. But for images
of land use/cover change (LUCC) obtained from the special spatial resolution remote sensing data, it will be of great significance
to obtain the land type area information with higher resolution by making use of spatial distribution characteristcs information
of the land type itself first and further scaling-down in a given scale threshold on the basis of the existing spatial resolution
data. An explicit expression of the relationship between the measurement scale, global fractal dimension and the land type
area corresponding to different measurement scales is obtained on the research basis of the authors’ histo-variogram using
the standardized area index (SAI). A good attempt has been made to obtain the land type area information with higher resolution
by merely using the spatial distribution characteristcs information of the land type in the image itself and further scaling-down
in a given scale threshold on the basis of the existing spatial resolution data.
Supported by the National Natural Science Foundation of China (Grant No. 40601068), the National Basic Research Program of
China (“973” Project) (Grant No. 2007CB714402) and the Key Science and Technology R&D Program of Qinghai Province (Grant No.
2006-6-160-01) 相似文献
11.
LI MiaoLing QI LeHua LI HeJun & XU GuoZhong School of Mechatronic Northwestern Polytechnical University Xi’an China Research Institute of Carbon-Carbon Composite Key Laboratory of Thermostructure Composite Material Northwestern Polytech- nical University 《中国科学E辑(英文版)》2009,52(4):871-877
A fractal characterization approach was proposed to research pore microstructure evolution in carbon/carbon (C/C) composites
during the chemical vapor infiltration process. The data obtained from mercury porosimetry determinations were analyzed using
the sponge fractal model and the thermodynamics relation fractal model, respectively. The fractal dimensions of C/C composites
at different densification stages were evaluated. The pore microstructure evolution with densification time was studied by
fractal dimension analysis. The results showed that C/C composites belong to porous fractal structure. The fractal dimensions
increase on the whole with decreasing porosity as the densification proceeds. The fractal dimensions are influenced by the
texture of pyrocarbon and decrease with increasing anisotropy from isotropic pyrocarbon to high textural one. Both the complicacy
of pore structure and the textural morphology of pyrocarbon can be represented simultaneously by the fractal dimension. The
pore evolution of C/C composites in the densification process can be monitored using fractal dimension.
Supported by the National Natural Science Foundation of China (Grant No. 50742008) 相似文献
12.
在对松辽盆地北部齐家-古龙地区泥岩裂缝油藏形成机理进行分析的基础上,应用盒式维数和信息维数计算了该区T2反射层不同区域内断层裂缝体系分维值。通过对各区断层裂缝体系分维特征的分析,发现断层裂缝体系分维高值区域与泥岩裂缝油藏的分布存在着较好的对应关系,这不仅表明断层伴生裂缝是该区泥岩裂缝的主要成因类型,同时也表明断层裂缝体系分维特征是定量描述泥岩裂缝油藏油气运移和聚集条件的一个重要参数。根据这一规律对该区泥岩裂缝油藏的有利分布区进行了预测。 相似文献
13.
The CH4/air premixed gas combustion processes in porous media were numerically studied using the two-temperature reacting
fluid model with dispersions and detailed chemical reaction mechanism GRI 3.0. The mechanisms of the propagation and stabilization
of submerge flames and surface flames in porous media were illuminated distinctly by considering the magnitude of the terms
in the two energy equations, analyzing the sensibility of flame propagation speed to flame location, heat exchange coefficient
between gas and solid, thermal conductivity and radiative extinction coefficient of porous media. It was concluded that the
propagation mechanism of a submerged flame is similar to that of a free flame with an additional preheat zone and that the
surface-flame propagation mechanism in porous media is similar to that of a free flame with heat loss in reaction zone.
Supported by the National Natural Science Foundation of China (Grant No. 50376060) 相似文献
14.
根据双重分形多孔介质孔隙分布分形维数D与孔隙迂曲分形维数DT的定义和计算公式,推导了多孔介质孔隙率的计算公式.通过孔隙率计算公式的函数图像分析了双重分形维数D和DT的变化对孔隙率的影响,分析结果表明孔隙率随多孔介质双重分形维数D和DT的增加而增大;多孔介质最大孔隙直径越大孔隙率增加的就越慢;当D+DT〈3时,多孔介质最大孔隙直径越大孔隙率就越大,但当D+DT〉3时则相反,多孔介质最大孔隙直径越大孔隙率反而越小,D+DT=3是特殊点,令D+DT→3时的孔隙率极限值为它的孔隙率. 相似文献
15.
A low mass flux steam jet in subcooled water was experimentally investigated. The transition of flow pattern from stable jet
to condensation oscillation was observed at relatively high water temperature. The axial total pressures, the axial and radial
temperature distributions were measured in the jet region. The results indicated that the pressure and temperature distributions
were mainly influenced by the water temperature. The correlations corrected with water temperature were given to predict the
dimensionless axial pressure peak distance and axial temperature distributions in the jet region, the results showed a good
agreement between the predictions and experiments. Moreover, the self-similarity property of the radial temperature was obtained,
which agreed well with Gauss distribution. In present work, all the dimensionless properties were mainly dependent on the
water temperature but weakly on the nozzle size under a certain steam mass flux.
Supported by the National Natural Science Foundation of China (Grant Nos. 50676078, 50821064) and the National High-Tech Research
and Development Program of China (“863” Project) (Grant No. 2006AA05Z230) 相似文献
16.
A physical modeling system of long slim tube was established. Several pressure measuring and sampling points were laid out
at different positions along the tube. Through real-time measurements of pressures and chemical concentrations at different
points, the mass transfer and chemical concentration of ASP flooding in porous media are studied. The concentration of chemicals
declines gradually during the fluid flow from the inlet to the outlet of the model. The concentration increases in the front
edge of the slug faster than the concentration decreases in the rear edge of the slug. The concentration variation of the
chemicals is an asymmetrical and offset process. The order of motion velocities of the chemicals from fast to slow is polymer,
alkali and surfactant. The motion lag and comprehensive diffusion are strong in the vicinity of the inlet, the motion velocities
of the chemicals are high, the difference of flow velocities among the three chemicals is significant and the chromatographic
separation of the chemicals is obvious. In the area near the outlet, the comprehensive diffusion and motion lag become weak,
the concentrations of the chemicals decrease, the motion velocities of the chemicals are slow, the difference among the motion
velocities of the chemicals becomes small, the chromatographic separation is not obvious, the adsorption and retention of
chemicals gradually increase as the chemical slug moves further along the tube, the adsorption and retention of polymer is
the most serious.
Supported by the National Basic Research Program of China (“973” Project) (Grant No. 2005CB221300) 相似文献
17.
LiXing Zhou 《中国科学E辑(英文版)》2008,51(8):1073-1086
The derivation and closure methods of the second-order moment (SOM) combustion model are proposed. The application of this
model to Reynolds averaged (RANS) and large-eddy simulation (LES) of turbulent swirling diffusion combustion, jet diffusion
combustion, and bluff-body stabilized premixed combustion is summarized. It is indicated that the SOM model is much better
than the eddy-beak-up (EBU) and presumed PDF models widely used in commercial software and engineering. The SOM modeling results
are close to those obtained using the most accurate but much more complex PDF equation model. Moreover, it can save much more
computation time than the PDF equation model. Finally, the SOM model is validated by the direct numerical simulation (DNS)
of turbulent reacting channel flows.
Supported by the National Natural Science Foundation of China (Grant Nos. 50606026 and 50736006), and the National Basic Research
Program of China (“973”) (Grant No. G-1999-0222-07) 相似文献
18.
考虑裂隙的多孔介质中对流扩散现象的仿真模拟 总被引:1,自引:0,他引:1
为研究裂隙多孔介质中的对流扩散现象,采用光滑粒子流体动力学(SPH)方法从孔隙尺度下模拟了裂隙中孔隙水的流动过程,仿真实现了考虑裂隙时溶质穿透多孔介质的真实运移过程,并提出一种简化处理的两流区模型对穿透过程加以描述.计算中首先采用SPH方法求解纳维斯托克斯方程,建立能考虑复杂多孔颗粒边界的二维流场模型,并基于此模型进行了溶质穿透三种不同裂隙宽度的多孔介质的仿真实验.随着介质中裂隙宽度增大,裂隙区域流速与基质区域流速差增大,穿透曲线中早期穿透和拖尾现象越明显;采用两流区模型能够描述这一现象,但一般化的模型难以得到精确解,因此提出一种简化处理办法,并给出了该简化模型的解析解.结果表明,该简化模型能够很好地描述裂隙多孔介质中溶质的运移规律,并可反演得到裂隙流中对流扩散的相关参数. 相似文献
19.
The coalbed methane transport model and its application in the presence of matrix shrinkage 总被引:1,自引:0,他引:1
Based on the theories of surface physical chemistry, theoretical formulations for permeability and porosity are presented
which include both stress effect and matrix shrinkage in a single equation. Then, a three-dimensional, dual porosity, nonequilibrium
adsorption, pseudosteady state mathematical model for gas and water is established and solved by the fully implicit method
and the block preconditioning orthomin algorithm. A history matching for the Qinshui Well TL003 is done. From the results,
it is shown that the obvious enhancement of permeability occurs along with the passing time but the reservoir pressure of
15# coal seam cannot fulfill the critical adsorption pressure as a result of the water recharge of the aquifer. Hence, it
is suggested to plug the 15# coal seam.
Supported by the National High Tech Research and Development Program of China (“863” Project) (Grant No. 2006AA06Z236) and
the National Basic Research Program (“973” Project) (Grant No. 2002CB11708) 相似文献
20.
Numerical modeling of concrete hydraulic fracturing with extended finite element method 总被引:2,自引:0,他引:2
The extended finite element method (XFEM) is a new numerical method for modeling discontinuity. Research about numerical modeling for concrete hydraulic fracturing by XFEM is explored. By building the virtual work principle of the fracture problem considering water pressure on the crack surface, the governing equations of XFEM for hydraulic fracture modeling are derived. Implementation of the XFEM for hydraulic fracturing is presented. Finally, the method is verified by two examples and the advan- tages of ... 相似文献