NONSTEADY FLOW OF GROUNDWATER IN AQUIFER SYSTEM WITH VISCOELASTIC PROPERTIES

The transient flow behavior of groundwater in aquifer-aquitard system withviscoelastic properties is studied.On the basis of previous works(Hantush,Neuman,Brutsaert,Corapcioglu),the new partial differential-integral equations are derived.Thewell-known equations(Hantush,Brutsaert) are the special cases of the new equations.Thenew equations describe the flow of a slightly compressible groundwater in layers withviscoelastic properties.Analytical solutions of the partial differential-integral equations are obtained by usingthe method of Laplace transform.The viscoelastic properties enhance the heterogeneities ofelastic aquifer system which have delay and feed qualities.The agreements between thenumericl inversion results of Laplace transform and the analytical solutions are good.Theformulae predict the transient flow behavior of groundwater in this heterogeneous layers.     

饱水土层的一维压密问题

1.问题的提出 大城市的地面沉降问题,近年来日益受到国内外人们的注意。如我国的上海市、意大利的威尼斯市的地面沉降,都是由于抽取大量地下水后所引起的。这些城市的地下水均埋藏在海陆交替相的第四纪地层中。这些覆盖层形成了含水层(由砂     

Mathematical model of two-phase fluid nonlinear flow in low-permeability porous media with applications

IntroductionItisasuccessfulexampleinadevelopmentstoryofscienceandtechnologyformechanicsoffluidsinporousmediatocombinewithengineeringtechnology .Fieldsinfluencedbythemechanicsinvolveddevelopmentofoil_gasandgroundwaterresources,controlonseawaterintrusionandsubsidenceandgeologichazards,geotechnicalengineeringandbioengineering ,andairlineindustry[1～ 7].Aproblemonnonlinearflowinlow_permeabilityporousmediaisbutonlyabasiconeindifferentkindsofengineeringfields,butalsooneoffrontlineresearchfieldsofmod…     

两相流体非线性渗流模型及其应用

基于三参数非线性渗流运动定律、质量守恒定律及椭圆渗流的概念,建立了低渗透介质中两相流体椭圆非线性渗流数学模型,运用有限差分法与外推法求得了其解,导出了两相流体椭圆非线性渗流条件下油井见水前后开发指标的计算公式,进行了实例分析。结果表明:非线性渗流对含水饱和度分布影响较大;非线性渗流使得水驱油推进速度比线性渗流的快,使油井见水时间提前,使得石油开发指标变差;非线性渗流使得同一时刻的压差比线性渗流的大,使石油开发难度加大。这为低渗油藏垂直裂缝井开发工程提供了科学依据。     

Dynamic production prediction and parameter identification for gas well with vertical fracture

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饱和粘土非线性渗流规律与径向固结

以多孔介质等效渗流概念得出粘土平均孔隙微尺度数量级范围在0.01 μm至0.1μm,与测试结果一致．实验结果表明饱和粘土微尺度孔隙渗流为非线性流．理论推导表明固液界面作用与渗透率平方根或孔隙半径成反比,固液界面相互作用是导致饱和粘土非线性渗流的重要原因．提出了精确描述饱和粘土微尺度孔隙非线性渗流基本规律的数学模型,其参数量纲明确,物理意义清楚．建立了饱和粘土非线性渗流新定律,统一描述了从较低到较高水力梯度全过程渗流曲线特征,达西定律是其特例．基于新定律,建立了饱和粘土非线性渗流定流量径向固结数学模型．以粘性边界层思想与稳态依序替换法及积分方程法,导出了粘土非线性渗流平均质量守恒方程及活动边界运动方程,给出了饱和粘土非线性渗流超孔隙水压力分布公式与平均固结度计算公式,获得了粘土层压力分布规律和平均固结度随时间变化规律．结果表明:饱和粘土非线性渗流使活动边界运动速度减小．研究结果为粘土地质工程与岩土工程应用提供了新的科学依据．达西渗流径向固结计算是新的非线性渗流固结计算的特例．     

Local discontinuous galerkin method for radial porous flow with dispersion and adsorption

Based on the local discontinuous Galerkin methods for time-dependent convection-diffusion systems newly developed by Corkburn and Shu, according to the form of the generalized convection-diffusion equations which model the radial porous flow with dispersion and adsorption, a local discontinuous Galerkin method for radial porous flow with dispersion and adsorption was developed, a high order accurary new scheme for radial porous flow is obtained. The presented method was applied to the numerical tests of two cases of radial porous, i. e. , the convection-dispersion flow and the convection-dispersion-adsorption flow, the corresponding parts of the numerical results are in good agreement with the published solutions, so the presented method is reliable. Reckoning of the computational cost also shows that the method is practicable.     

低渗透介质含启动压力梯度一维瞬时压力分析

考虑启动压力梯度的影响,本文得到了在一维低渗透岩心和圆形油藏中一开一关渗流的数学方程,并进行有动边界问题的数值求解。以数值解为基础,分析了:1.渗流终态时井底(或岩心采液端)压力及压力影响半径(或距离)与启动压力梯度和关闭时间的关系,并给出相应的公式;2.压力峰值的传播规律。得到了有意义的结果,为低渗透油藏开发室内实验和现场应用提供理论基础。     

二阶非牛顿流体环管流动解析解

本文采用积分变换的方法,找到了一类非牛顿流体在环形管道中不定常流动的解析解,并进行了数值计算,详尽分析了非牛顿性系数和其他各参数对二阶流体不定常流动的影响.指出当二阶流体非牛顿系数相同时,环管流与一般管流相比达到稳定的特征时间较短,并且相应的速度分布、平均速度分布的数值均较小,在外半径相同时,环管流内壁的剪应力较之一般管流,其大小随内半径的大小而变,环管流的外壁剪应力总相应地小于内壁剪应力.     

环空管内粘弹性流体不定常旋转流的解及流动特性分析

本文用Hankel积分变换法分别求得二阶流体和Maxwell流体在环管内不定常旋转流运动方程的解析解,据此可以分析环管内旋转速度和切应力的分布与变化特征;流体物性参数、管道环隙大小等参量在解析公式中有明确反映,便于定性分析和讨论,本解可以为钻探工程和高分子加工工艺的设计提供理论依据,另外还可用来分析双筒粘度计的流动状态和应力特征,拟合曲线,确定材料的粘弹性参数,在对这种流体进行特性分析时,我们发现,Maxwell流体的旋转流动在起动初期表现为方波振荡,振动的幅度和周期随Ha(物质常数)的增大而增大,此种现象还是首次发现,可能对实际应用有一定的意义。