聚合物驱相对渗透率曲线及影响因素试验研究

本文从聚合物溶液在多孔介质中流动的特点出发，在考虑渗率降低系数和多孔介质中流变特性的基础上，建立了聚合物驱相对渗透率计算方法，利用驱替试验数据，用本文方法和不考虑多孔介质中流变性两种方法分别计算出聚合物驱相对渗透率。分析研究了水驱与聚合物驱相对渗透率曲线的差异。研究了多孔介质中剪切速率对计算的影响以及聚合物浓度。注入速度对聚合物驱相对渗透率的影响。     

弱凝胶调驱降维数值模拟方法研究

目前用于弱凝胶调驱的化学驱软件大多存在计算速度慢、数值弥散现象严重的问题,为了提高弱凝胶调驱数值模拟的速度和精度,提出了降低维数的模拟方法。利用追踪流线的方法,将弱凝胶调驱的三维渗流问题,转化为沿流线计算饱和度的一维问题,大大降低了求解饱和度方程组中方程的数目,从而提高了计算速度。利用该方法,模拟了玉门老君庙油田一个试验井区的水驱开发历史,优化了弱凝胶调驱的注入浓度、注入速度及注入体积等参数,并预测了弱凝胶调驱的动态,预测该方案可提高采收率7.6%。     

聚合物驱微观渗流实验剩余油分布的定量分析研究

聚合物驱微观渗流实验是研究聚合物驱微观渗流机理，认识剩余油分布及形态的有效手段。利用图像处理技术，提出了一整套聚合物驱微观渗流图像的定量化分析方法，包括图像预处理、图像分割剩余油和孔隙、孔隙结构的分形维数研究、剩余油几何形状特征的描述、以及渗流参数的计算等。应用实例验证了方法的有效性，定量分析结果表明，在聚合物驱初期，剩余油以条带状和网络状为主；在驱替中期，由于聚合物的粘弹性作用，剩余油富集带形成，网络状剩余油占了较大比例；在驱替末期，剩余油以斑状、条带状和网络状为主。     

大型水轮发电机组主轴系统动力特性研究现状及建模方法

水轮发电机组动态特性研究的关键，在于建立正确的数学模型、确定重要零部件边界条件以及采用稳定、高精度的求解方法。本文论述了机组主轴系统动态响应的求解现状及建模方法，分析了几个重要相关零部件的边界条件确定，即支承部件的动力学建模问题。     

排水农田氮素运移,转化及流失规律的研究

在总结文献和室内外试验基础上，对排水条件下氮素运移，转化及流失规律进行了分析研究；建立了一维、二维土壤水和地下水中氮素运移转化数学模型；探索了有限元数值计算法耦合求解水流和氮素运移模型，并提出了改进流线追踪法，克服已有简易计算方法中采用经验数据，精确方法计算繁复，且耗机时多的缺点，可用于排水农田氮素运移长期预报。     

辽河常规稠油油藏的聚合物驱问题研究

稠油油聚聚合物驱是一个很敏感的问题。本文以目前仍采用水驱的常规稠油油藏为研究对象，在天然岩心，人造岩心和平面模型中进行室内实验，主要研究了常规同油藏水驱后进行聚合珠驱的驱油效率和驱替特征；同时，用核磁共振成像技术研究了其驱油机理。     

闸下有压渗流的边界拟合坐标变换数值解

建立了曲线拟合坐标系下闸下渗流的数学模型，给出了边界条件和求解方程。计算实例表明，该数学模型对水利工程中的复杂边界渗流的数值求解很有效，可应用于工程实际。     

丁坝附近垂线平均的二维流动计算

矩形河渠中丁坝附近垂线平均流速和床面剪切应力分布可用垂线平均的二维模型进行计算，该模型运用混合有限差分格式和迭代法求解水流和湍流输移的控制方程，由于坝头附近区域受流线弯曲的影响，在ｋ－ε湍流模型中引入了一个修正系数，这与以前的数值计算方法相比，流速和流线图的计算与试验数据间的吻合程度得到了明显改善，实际表明，该区域的床面剪应力主要受三维流动的影响，引入一个三维修正系数可大大地改善床面剪应力计算值，     

溢流坝坝面压力分布的数值计算和讨论

本文利用变区域上变分有限元方法求解了溢流坝自由溢流和闸下出流问题。溢流流量、自由面形状以及流线位置和坝面上的压力分布等均可通过求解一组非线性方程组同时得到。文中对各种坝面形状和有、无闸门情况给出了大量的坝面压力分布计算值,并与相应的模型实验值和野外实测值进行了比较。结果表明,本文的数值计算基本上能判断出坝面上的压力分布形态和最大负压值及其位置,但下游(X/Hd>1.2)处的压力计算值与实测值有较大误差。因而,文中还讨论了理想流体流动下游边界条件(7)的近似性并提出了进一步改进的设想。     

深覆盖层动态模型中阻尼及边界条件的研究

在深覆盖层振动反应分析中,动态模型的阻尼及边界条件对其动态特性影响较大。基于有限元法考虑土层的非线性阻尼特性,采用不同的边界条件及阻尼参数取值方法,分别建立深覆盖层有限元动态模型,对深覆盖层进行时域的动力分析,并与传统的频域等效线性法计算结果进行对比。结果表明:在四周及底部施加粘弹性边界,同时运用邹德高阻尼计算方法的动态模型能够较好的反应深覆盖层振动特性。     

A STREAMLINE-BASED PREDICTIVE MODEL FOR ENHANCED-OIL-RECOVERY POTENTIALITY

A pseudo-three-dimensional model of potentiality prediction is proposed for enhanced oil recovery, based on the streamline method described in this article. The potential distribution of the flow through a porous medium under a complicated boundary condition is solved with the boundary element method. Furthermore, the method for tracing streamlines between injection wells and producing wells is presented. Based on the results, a numerical solution can be obtained by solving the seepage problem of the stream-tube with consideration of different methods of Enhanced Oil Recovery（EOR）. The advantage of the method given in this article is that it can obtain dynamic calculation with different well patterns of any shape by easily considering different physicochemical phenomena having less calculation time and good stability. Based on the uniform theory basis-streamline method, different models, including CO2 miscible flooding, polymer flooding, alkaline/surfactant/polymer flooding and microbial flooding, are established in this article.     

SIPSON--simulation of interaction between pipe flow and surface overland flow in networks.

The new simulation model, named SIPSON, based on the Preissmann finite difference method and the conjugate gradient method, is presented in the paper. This model simulates conditions when the hydraulic capacity of a sewer system is exceeded, pipe flow is pressurized, the water flows out from the piped system to the streets, and the inlets cannot capture all the runoff. In the mathematical model, buried structures and pipelines, together with surface channels, make a horizontally and vertically looped network involving a complex interaction of flows. In this paper, special internal boundary conditions related to equivalent inlets are discussed. Procedures are described for the simulation of manhole cover loss, basement flooding, the representation of street geometry, and the distribution of runoff hydrographs between surface and underground networks. All these procedures are built into the simulation model. Relevant issues are illustrated on a set of examples, focusing on specific parameters and comparison with field measurements of flooding of the Motilal ki Chal catchment (Indore, India). Satisfactory agreement of observed and simulated hydrographs and maximum surface flooding levels is obtained. It is concluded that the presented approach is an improvement compared to the standard "virtual reservoir" approach commonly applied in most of the models.     

An effective method to predict oil recovery in high water cut stage

The water flooding characteristic curve method based on the traditional regression equation between the oil and water phase permeability ratio and the water saturation is inappropriate to predict the oil recovery in the high water cut stage. Hence, a new water flooding characteristic curve equation adapted to the high water cut stage is proposed to predict the oil recovery. The water drive phase permeability experiments show that the curve of the oil and water phase permeability ratio vs. the water saturation, in the semi-logarithmic coordinates, has a significantly lower bend after entering the high water cut stage, so the water flooding characteristic curve method based on the traditional regression equation between the oil and water phase permeability ratio and the water saturation is inappropriate to predict the oil recovery in the high water cut stage; therefore, a new water flooding characteristic curve equation based on a better relationship between ln( k_(ro)/k_(rw)) and S w is urgently desirable to be established to effectively and reliably predict the oil recovery of a water drive reservoir adapted to a high water cut stage. In this paper, by carrying out the water drive phase permeability experiments, a new mathematical model between the oil and water phase permeability ratio and the water saturation is established, with the regression analysis method and an integration of the established model, the water flooding characteristic curve equation adapted to a high water cut stage is obtained. Using the new water flooding characteristic curve to predict the oil recovery of the GD3-block of the SL oilfield and the J09-block of the DG oilfield in China, results with high predicted accuracy are obtained.     

Application of binding theory for seepage of viscoelastic fluid in a variable diameter capillary

The polymer solution for polymer flooding is a viscoelastic fluid. There exist both shear flow and elongational flow when the polymer solution flows in a porous medium, where an additional dissipation is involved. The additional dissipation caused by elongational deformation is often ignored while studying the flow of the fluid in a porous medium. For a complex polymer solution, the generated elongational pressure drop cannot be ignored. In a capillary of fixed diameter, the polymer solution is only impacted by the shear force, and its rheological property is pseudoplastic. Therefore the variable diameter capillary and the converging-diverging flow model with different cross sections are required to describe the flow characteristics of the polymer solution in porous media more accurately. When the polymer solution flows through the port, we have the elongational flow and the polymer molecules undergo elongational deformation elastically. By using the mechanical energy balance principle and the minimum energy principle, a mathematical model of non-Newtonian fluid inlet flow was established by Binding. On the basis of the Binding theory, with the application of the theory of viscoelastic fluid flow in the circular capillary and the contraction-expansion tube, the relations between the viscoelastic fluid flow rate and the pressure drop are obtained.     

AN UNSTEADY SEEPAGE FLOW MODEL OF VISCO-ELASTIC POLYMER SOLUTION

With the consideration of the visco--elasticity, the adsorption effect and the variation of rheological parame ters, a seepage flow model of visco-elastic polymer solutions was established. The model was numerically treated with the finite difference method. Then curves of Bottom Hole Pressure (BHP) and formation pressure were drawn. The influences of the relaxation time, the injection rate, the permeability reduction co,efficient, the consistency coefficient and the power-law exponent of the injected fluid on pressure performance were analyzed. This study shows that it is necessary to consider the visco elasticity of non-Newtonian fluid in analyzing of pressure performance in the polymer flooding.     

High-resolution flood modeling of urban areas using MSN_Flood

Although existing hydraulic models have been used to simulate and predict urban flooding, most of these models are inadequate due to the high spatial resolution required to simulate flows in urban floodplains. Nesting high-resolution subdomains within coarser-resolution models is an efficient solution for enabling simultaneous calculation of flooding due to tides, surges, and high river flows. MSN_Flood has been developed to incorporate moving boundaries around nested domains, permitting alternate flooding and drying along the boundary and in the interior of the domain. Ghost cells adjacent to open boundary cells convert open boundaries, in effect, into internal boundaries. The moving boundary may be multi-segmented and non-continuous, with recirculating flow across the boundary. When combined with a bespoke adaptive interpolation scheme, this approach facilitates a dynamic internal boundary. Based on an alternating-direction semi-implicit finite difference scheme, MSN_Flood was used to hindcast a major flood event in Cork City resulting from the combined pressures of fluvial, tidal, and storm surge processes. The results show that the model is computationally efficient, as the 2-m high-resolution nest is used only in the urban flooded region. Elsewhere, lower-resolution nests are used. The results also show that the model is highly accurate when compared with measured data. The model is capable of incorporating nested sub-domains when the nested boundary is multi-segmented and highly complex with lateral gradients of elevation and velocities. This is a major benefit when modelling urban floodplains at very high resolution.     

A 3-D SPH model for simulating water flooding of a damaged floating structure

With the quasi-static analysis method, the terminal floating state of a damaged ship is usually evaluated for the risk assessment. But this is not enough since the ship has the possibility to lose its stability during the transient flooding process. Therefore, an enhanced smoothed particle hydrodynamics(SPH) model is applied in this paper to investigate the response of a simplified cabin model under the condition of the transient water flooding. The enhanced SPH model is presented firstly including the governing equations, the diffusive terms, the boundary implementations and then an algorithm regarding the coupling motions of six degrees of freedom(6-DOF) between the structure and the fluid is described. In the numerical results, a non-damaged cabin floating under the rest condition is simulated. It is shown that a stable floating state can be reached and maintained by using the present SPH scheme. After that, three-dimensional(3-D) test cases of the damaged cabin with a hole at different locations are simulated. A series of model tests are also carried out for the validation. Fairly good agreements are achieved between the numerical results and the experimental data. Relevant conclusions are drawn with respect to the mechanism of the responses of the damaged cabin model under water flooding conditions.     

STUDY FOR STREAMLINE OF ARBITRARY SHAPED HOMOGENEOUS RESERVOIRS WITH IMPERMEABLE BARRIERS

1. INTRODUCTION The streamline distributions can visualy display the reservoir fluid’s movement tracks between the producers and injectors, and determine the area and shape of displacement. An optimum pattern and an injection strategy also can be develop…