超临界CO_2动态混相驱过程机理研究

以国内CS油田注CO2混相驱典型实例为基础,在油藏地层流体注CO2驱膨胀实验和细管最小混相压力实验拟合基础上,建立一维组分注气驱细管模型。应用所建立的模型,模拟研究CO2注入过程中油气两相组成、油气两相黏度、密度和界面张力等动态特性参数沿注气井到生产井距离的变化规律。以及注气量和注气压力对动态特性参数的影响规律。研究结果显示:CO2在原油中的溶解能力强,工程混相条件下,摩尔含量达到0.7。注入CO2抽提原油中的中间烃,甚至C19+以上的重烃,与地层油在前缘达到混相。CO2注入量增加,混相带增长,CO2波及区域增加,有利于驱油效率增加。随着注入压力的提高,从非混相到混相,CO2在地层油中的溶解量增加,界面张力降低,油的黏度降低。达到混相后,继续增加压力对驱油影响变小。

Wavefield simulation in porous media saturated with two immiscible fluids

Wavefields in porous media saturated by two immiscible fluids are simulated in this paper.Based on the sealed system theory,the medium model considers both the relative motion between the fluids and the solid skeleton and the relaxation mechanisms of porosity and saturation（capillary pressure）.So it accurately simulates the numerical attenuation property of the wavefields and is much closer to actual earth media in exploration than the equivalent liquid model and the unsaturated porous medium model on the basis of open system theory.The velocity and attenuation for different wave modes in this medium have been discussed in previous literature but studies of the complete wave-field have not been reported.In our work,wave equations with the relaxation mechanisms of capillary pressure and the porosity are derived.Furthermore,the wavefield and its characteristics are studied using the numerical finite element method.The results show that the slow P3-wave in the non-wetting phase can be observed clearly in the seismic band.The relaxation of capillary pressure and the porosity greatly affect the displacement of the non-wetting phase.More specifically,the displacement decreases with increasing relaxation coefficient.

The Influence of Glucose on Numerical Simulation of a Vascular Solid Tumor Growth

Glucose is the mainly nutrient substances in tumor growth,which played an important role in tumor cells' growth,proliferation and immigration.Numerical simulation will help a good understanding for the influence of glucose which affected on a vascular solid tumor growth.We present a hybrid on-Lattice Model to simulate the influence of glucose on a-vascular tumor growth.The hybrid model we developed focuses on five key variables implicated in the invasion process:tumor cells,extracellular matrix,matrix-degradative enzymes,oxygen and glucose.And about the discrete model,we consider cell evolution dynamics on cell level.Results indicate that the number of proliferation and quiescent cells is decreasing by decreasing the initial glucose concentration,consequently increase necrotic area relatively.Thus there is inhabitation effect on tumor growth by decreasing initial glucose concentration.

Simulation of Thermocapillary Convection in a TwoLayer Immiscible Fluid System Using a Boundary Element Method

A boundary element method for simulating thermocapillary convection in a two-layer immiscible fluid system with flat and free interface has been developed.The divergence theorem is applied to the non-linear convective volume integral of the boundary element formulation with the pressure penalty function.Consequently,velocity gradients are eliminated and the complete formulation is written in terms of velocity.This avoids the difficulty of convective discretizations and provides considerable reductions in storage and computational requirements while improving accuracy.In this paper,we give the influence of different parameters(Marangoni number, Reynolds number)on thermocapillary convection in cavity with two-layer immiscible fluids.As shown by the numerical results,when the physical parameters between liquid encapsulant and melt are chosen appropriately, the detrimental flow in the bottom melt layer can be greatly suppressed.The influence of the free interface on thermocapillary convection is also shown.

Supplement and optimization of classical capillary number experimental curve for enhanced oil recovery by combination flooding

In the middle of the last century,American scientists put forward the concept of capillary number and obtained the relation curve between capillary number and residual oil through experiments.They revealed that the corresponding residual oil saturation decreased with increasing of capillary number;after capillary number reached up to a limit,residual oil saturation would become stable and did not decrease.These important achievements laid a theoretical base for enhanced oil recovery with chemical flooding.On the basis of the theory,scholars developed chemical flooding numerical simulation software UTCHEM.During the numerical simulation study of combination flooding,the authors found that as the capillary number is higher than the limit capillary number,the changes of the residual oil saturation along with the capillary number differ from the classical capillary number curve.Oil displacement experiments prove that there are defects in classic capillary number experimental curve and it is necessary to mend and improve.Capillary number‘calculation’curve is obtained with a method of numerical simulation calculation and a complete description of capillary number curve is provided;On this basis,combination flooding capillary number experimental curve QL is obtained through experiments,which is different from the classical capillary curve;and based on which,an expression of corresponding combination flooding relative permeability curve QL is given and the corresponding relative permeability parameters are determined with experiments.Further oil displacement experiment research recognizes the cause of the singular changes of the capillary number curve."Combination flooding capillary number experimental curve QL"and"combination flooding relative permeability curve QL"are written in combination flooding software IMCFS,providing an effective technical support for the application of combination flooding technical research.