贝雷砂岩射孔孔道流动效应正交计算分析

对射孔孔道流动效应进行了量纲分析,建立了轴向和径向流量与影响流量因素间的工程表达式。综合考虑影响流动效应的主要因素和取值范围,设计了数值模拟计算工况的正交计算方案,并利用ANSYS/FLOTRAN流体程序进行了带损伤区贝雷砂岩流量数值模拟研究,获得了各个计算方案的径向流量和轴向流量,用以确定出流量公式的系数。最终确定的流量公式表明,各要素对流量影响的重要顺序依次为固有渗透率、损害区厚度、孔深、渗透率剩余百分数和孔径。     

Pore Scale Modeling of Rate Effects in Imbibition

We use pore scale network modeling to study the effects of flow rate and contact angle on imbibition relative permeabilities. The model accounts for flow in wetting layers that occupy roughness or crevices in the pore space. Viscous forces are accounted for by solving for the wetting phase pressure and assuming a fixed conductance in wetting layers. Three-dimensional simulations model granular media, whereas two-dimensional runs represent fracture flow.We identify five generic types of displacement pattern as we vary capillary number, contact angle, and initial wetting phase saturation: flat frontal advance, dendritic frontal advance, bond percolation, compact cluster growth, and ramified cluster growth. Using phase diagrams we quantify the range of physical properties under which each regime is observed. The work explains apparently inconsistent experimental measurements of relative permeability in granular media and fractures.     

In vivo transdermal delivery using a shock tube

A shock tube was utilized for transdermal delivery in fuzzy rats. Rhodamine-B dextran, 10 kDa molecular weight, was used as the probe molecule. Shock waves were generated by a two-stage shock tube. A single shock wave was applied onto the skin to permeabilize the stratum corneum. Subsequently, the dextran solution diffused through the stratum corneum into the epidermis. Fluorescence microscopy of biopsies showed that the dextran was delivered to a depth of m into the skin. Thus, the shock tube could become an inexpensive device for transdermal drug delivery. Received 19 February 2000 / Accepted 29 June 2000     

A Mathematical Model for Hysteretic Two-Phase Flow in Porous Media

We develop a mathematical model for hysteretic two-phase flow (of oil and water) in waterwet porous media. To account for relative permeability hysteresis, an irreversible trapping-coalescence process is described. According to this process, oil ganglia are created (during imbibition) and released (during drainage) at different rates, leading to history-dependent saturations of trapped and connected oil. As a result, the relative permeability to oil, modelled as a unique function of the connected oil saturation, is subject to saturation history. A saturation history is reflected by history parameters, that is by both the saturation state (of connected and trapped oil) at the most recent flow reversal and the most recent water saturation at which the flow was a primary drainage. Disregarding capillary diffusion, the flow is described by a hyperbolic equation with the connected oil saturation as unknown. This equation contains functional relationships which depend on the flow mode (drainage or imbibition) and the history parameters. The solution consists of continuous waves (expansion waves and constant states), shock waves (possibly connecting different modes) and stationary discontinuities (connecting different saturation histories). The entropy condition for travelling waves is generalized to include admissible shock waves which coincide with flow reversals. It turns out that saturation history generally has a strong influence on both the type and the speed of the waves from which the solution is constructed.     

General Anisotropic Effective Medium Theory for the Effective Permeability of Heterogeneous Reservoirs

One of the techniques to calculate the effective property of a heterogeneous medium is the effective medium theory. The present paper presents a general mathematical formulation for the effective medium approximation using a self-consistent choice of the effective permeability, to apply it to the case of a general anisotropic 2D medium and to the case of a 3D isotropic medium with randomly oriented ellipsoidal inclusions. The 2D results are compared with analytical results and with a homogenization technique with good result. The 3D correlations are used to derive percolation thresholds in two-phase systems with a large permeability contrast, which are compared to numerical results from the literature, also with good results.     

用喷涂晶种法ZSM-5合成沸石膜及其影响因素考察

在多孔α－Ａｌ２Ｏ３载体上,采用喷涂方法引入一层晶种,再用水热法合成出渗透量大、气体选择分离系数高的ＺＳＭ－５沸石膜;对影响ＺＳＭ－５沸石膜合成的主要因素进行卫考察,并用ＸＲＤ,ＳＥＭ及单组分气体渗透性能测定对所合成的沸石膜进行了表征。结果表明,所合成的沸石膜是典型的ＺＳＭ－５沸石膜,膜表面晶粒排列有序,整齐地连成一致密层,绝大部分晶粒的取向一致,无较大裂缺存在,经一次合成的沸石膜的Ｈ２渗透率可达     

稠油油藏高温盐析调剖的孔渗表征方法研究

深层高温油藏在开采过程中,由于近井地带压力变化剧烈,地层水蒸发致使结晶盐析出,进而导致储层孔隙度、渗透率降低.为研究稠油油藏高温盐析调剖的孔渗变化规律,根据盐类溶解/沉淀原理及储层孔隙度渗透率关系和填砂管模型高温盐析实验结果,建立了考虑地层水蒸发、水中氯化钠析出和储层孔渗变化的综合盐析模型.研究结果表明:随着堵剂注入量增加,封堵率快速上升并趋于稳定;实验温度在200~500℃之间氯化钠堵剂具有较好的封堵效果;盐析调堵方法可以有效封堵储层气窜通道,改良吸气剖面,提高周期采油量.最后用实验结果对数学模型进行拟合修正,得到稠油油藏高温盐析调剖的孔渗表征方法.     

Steady flow in a deformable porous medium

A nonlinear model for a steady flow in a deformable porous medium is considered. The flow is governed by the poroelasticity system consisting of an elasticity equation for the displacement of the porous medium and Darcy's equation for the pressure in the fluid. This poroelasticity system is nonlinear when the permeability in Darcy's equation is assumed to depend on the dilatation of the porous medium. Existence and uniqueness of a weak solution of this poroelasticity system is established under rather weak assumptions on the regularity of the data. Convergence of a finite element approximation is proved and verified through numerical experiments. Copyright © 2013 John Wiley & Sons, Ltd.     

Diffusion of gases across lipid membranes with OmpA channel: a molecular dynamics study

Molecular transport across biological membranes occurs in a range of important chemical and biological processes. The biological membrane can usually be modelled as a phospholipid bilayer, but to correctly represent biological transport, the embedded transmembrane proteins must also be included. In previous molecular simulation studies on transport of small gas molecules in dipalmitoylphosphatidylcholine (DPPC) bilayer membrane, a coarse-grained model was used to provide direct insight into collective phenomena in biological membranes. Coarse graining allowed investigation of longer time and length scales by reducing the degrees of freedom and employing suitable potentials. In this work, membranes that include transmembrane proteins are modelled. This allows one to compare the molecular transport across a lipid membrane with and without the assistance of transmembrane channels. Outer membrane protein A (OmpA) – a porin from Escherichia coli with a small pore size – was chosen in this study because its detailed structure is known, it has high stability and is known to form a nonspecific diffusion channel that permits the penetration of various solutes. In this work the pore characteristics and interaction between lipid and protein were investigated and transport of water and other small gas molecules within the channel were studied. The MD simulation results obtained are compared with previous simulation results and available experimental data. The results obtained from this study will lead to better understanding of protein functionality and advance the development of biochips and drug delivery systems.     

Adjustable microwave permeability of nanorings: A micromagnetic investigation

Based on the three-dimensional micromagnetic simulations, we present a method to tailor the microwave permeabilities of magnonic metamaterials cells by a designed nanoring structure. The results show that the permeabilities and resonant frequency are depended on the wall?s thickness of nanorings. The underlying mechanism is ascribed to the presence of strong demagnetization fields, which are associated to the ring?s wall. In addition, the products of magnetic susceptibility and resonant frequency are larger than that predicted from Snoek?s law in polycrystalline particles. These results are direct manifestations of the bi-anisotropy model.