The Determination of Effective Diffusivity Coefficients in a Solvent Gas Heavy Oil System for Methane

Abstract

In this investigation, an accurate high pressure and temperature diffusion setup was applied to measure the diffusion coefficients of methane in Iranian heavy oils in presence and absence of porous media by using the pressure-decay method. The solvent diffusivity in heavy oil was determined by both graphical and numerical methods. In addition, the effects of the porous medium and the temperature on the molecular diffusion coefficient of the solvent gas in the liquid phase were discussed and finally, using experimental data, a functionality dependence of molecular diffusivity on temperature and porous medium characteristics was proposed.     

Mass Transfer of CO2 Into Water and Surfactant Solutions

The mass transfer of CO₂ into water and aqueous solutions of sodium dodecyl sulphate (SDS) is experimentally studied using a pressure, volume, temperature (PVT) cell at different initial pressures and a constant temperature (T = 25°C). It is observed that the transfer rate is initially much larger than expected from a diffusion process alone. The model equations describing the experiments are based on Fick's Law and Henry's Law. The experiments are interpreted in terms of two effective diffusion coefficients—one for the early-stages of the experiments and the other one for the later stages. The results show that at the early stages, the effective diffusion coefficients are one order of magnitude larger than the molecular diffusivity of CO₂ in water. Nevertheless, in the later stages the extracted diffusion coefficients are close to literature values. It is asserted that at the early stages, density-driven natural convection enhances the mass transfer. A similar mass transfer enhancement was observed for the mass transfer between a gaseous CO₂ rich phase with an oil (n-decane) phase. It is also found that at the experimental conditions studied addition of pure SDS does not have a significant effect on the mass transfer rate of CO₂ in water.     

Mass Transfer of CO2 Into Water and Surfactant Solutions

Abstract

The mass transfer of CO₂ into water and aqueous solutions of sodium dodecyl sulphate (SDS) is experimentally studied using a pressure, volume, temperature (PVT) cell at different initial pressures and a constant temperature (T = 25°C). It is observed that the transfer rate is initially much larger than expected from a diffusion process alone. The model equations describing the experiments are based on Fick's Law and Henry's Law. The experiments are interpreted in terms of two effective diffusion coefficients—one for the early-stages of the experiments and the other one for the later stages. The results show that at the early stages, the effective diffusion coefficients are one order of magnitude larger than the molecular diffusivity of CO₂ in water. Nevertheless, in the later stages the extracted diffusion coefficients are close to literature values. It is asserted that at the early stages, density-driven natural convection enhances the mass transfer. A similar mass transfer enhancement was observed for the mass transfer between a gaseous CO₂ rich phase with an oil (n-decane) phase. It is also found that at the experimental conditions studied addition of pure SDS does not have a significant effect on the mass transfer rate of CO₂ in water.     

Analytical Analysis for Mass Transfer in a Fractured Porous Medium

The aim was to analyze the transient behavior of mass transfer in a fractured porous medium. The jump condition that applies between the two regions (porous media and fracture) considers a transient term with an adjustable parameter (γ). In order to know more about the γ parameter, the problem under consideration in this work is the adsorption in a porous medium adjacent to a fluid (acts as fracture). The analytical solution for the concentrations in the porous media and in the homogeneous flow coupled by a jump condition with accumulation effects was obtained using the Laplace method.     

The Application of Numerical Laplace Inversion Methods for Type Curve Development in Well Testing: A Comparative Study

Abstract

In this work the Fourier series and Zakian and Schapery methods are considered to numerically solve the Laplace transform of a pressure distribution equation for radial flow and to generate the type curves for three different boundary conditions. The results show that the Schapery method leads to approximate solutions for small values of dimensionless time. For large values, however, this method is almost accurate and hence is recommended because it is fast to apply compared to other algorithms. It has been found that the accuracy of the Schapery method for early time prediction can be improved to almost a perfect match with analytical results through multiplying the Schapery relation by a proposed constant coefficient. This coefficient, regardless of the condition in the external boundary, is set to 0.58 when the wellbore storage effect and skin factor are considered. For an infinite acting case, when C_D and S are included, and also for constant pressure case, all the methods fail to predict the behavior of the derivative plot accurately at late times, whereas other cases showed acceptable accuracy. At middle times, no analytical solution is available to check the accuracy of numerical methods, but because all the methods discussed here showed identical results, it is reasonable to trust in numerical inversion calculations.     

极限扩散电流技术测定管内强化传质系数

采用极限扩散电流技术(LDCT)测定管内液体传质系数(k),通过使用静态混合器、筛板和不锈钢θ环填料与筛板耦合体等强化元件,考察了不同强化手段对管内k的影响,研究了气液多相体系的传质过程。实验结果表明,LDCT能较好地测定单相和多相体系的k。在液体流量为1.00m3/h的条件下,空直管中的k为2.38×10-2m/s;使用筛板、静态混合器和填料与筛板耦合体时,k分别为3.64×10-2,3.96×10-2,5.90×10-2m/s。由实验测定的k结合传递类比定律可得到液体传热系数。     

碳酸水-原油体系中CO2分子的扩散行为

CO2分子在油水相间的扩散传质行为对于致密油藏注CO2提高釆收率具有重要意义.通过融合实验测定数据和理论扩散模型,利用试错法同时确定了碳酸水-原油二元体系中CO2分子在油、水两相中的扩散系数.重点研究了油水混合体系的初始压力对扩散系数的影响规律,深入探讨了扩散过程中油水相密度、CO2浓度、油水界面移动以及CO2在油相中...     

水敏性低渗透储层油水两相渗透率JBN计算方法的改进

水敏性低渗透砂岩在水驱油过程中由于受到黏土膨胀、颗粒运移、堵塞等水敏影响,岩石的孔隙半径缩小、渗透率降低,出现注入压力异常的现象,采用常规的JBN方法计算油水两相渗透率会出现异常的相渗曲线。在考虑水敏性低渗透砂岩水驱油过程中水敏影响的基础上,对常规JBN解释方法进行了改进,以满足正确解释水敏性低渗透砂岩油水两相渗透率的需要,实例应用证实了改进方法的正确性与实用性。     

气体搅拌萃取塔传质系数的研究

为研究萃取塔内气体搅拌对传质系数的影响,在萃取塔中用水萃取煤油中的苯甲酸的实验考察了液相流速、气体流速和内构件对传质系数的影响。实验结果表明,传质系数随水、油、气的表观流速的增加而增加,分散相表观流速对传质系数的影响大于连续相的表观流速;萃取塔内构件的不同组合方式对传质系数有一定的影响,其中以SL-SP-SL型组合方式的传质效果最好。     

莫北油气田三工河组油气藏油气水分布规律及油藏类型

莫北油气田三工河组油气藏油气水分布主要受构造控制,在J1S21油藏受岩相控制较明显.以地震、地质研究及试油、试采资料为依据,对试油资料不足的区块结合五种经验判别方法(Φ1参数判别法、C5+含量判别法、C1/C5+比值判别法、F参数等级分类判别法和Z因子判别法)进行综合分析.莫北2井区J1S21砂层油气界面仍需通过评价井MB2003井试油才能落实,油气藏类型为层状低孔低渗、带边水的凝析油气藏;J1S22砂层据开发评价井MB2003井测井曲线和三维地震解释,结合该井试油成果资料,确定了油水界面,油气藏类型为带油环带边底水的低孔低渗凝析气藏.莫北9井区块J1S21和J1S22分属两个不同油藏.J1S22为构造油藏,J1S21为受岩性控制的构造油藏.     

异丁烷/丁烯固体酸烷基化固定床反应器模型研究

针对异丁烷/丁烯固体酸烷基化固定床工艺过程,建立了一维动态传质模型,并对点活性与有效扩散系数的关联式进行了修正。模型计算结果与实验数据吻合良好,验证了模型的准确性。考察了反应器内烯烃和点活性的时空分布情况,并确定了固体酸催化剂失活的主要原因：反应器入口处,活性位覆盖是催化剂失活的主要原因;随着反应器床层高度增加,孔道堵塞逐渐成为催化剂失活的主要原因。     

井筒内气体扩散侵入定量计算模型

油基钻井液中更易发生气体扩散侵入,伴随油基钻井液使用的增多,有必要研究气体扩散侵入的机理并建立气体扩散侵入定量计算模型。将气体扩散侵入通道划分为气体与滤液界面、滤液滞留区、内滤饼区、外滤饼区、外滤饼区内壁与钻井液界面5个部分,在分析气体扩散侵入机理的基础上,推导了井筒内气体扩散侵入控制方程及解析解。基于解析解,给出了气体扩散侵入参量(循环工况气体侵入速率、循环工况井筒内气体总量、静止工况气体最大浓度、静止工况井筒内气体总量)的定量计算公式。结合算例分析,得到了储层长度、储层孔隙度、钻井液滤失对气体扩散侵入的影响规律。除了静止工况最大气体浓度外,气体扩散侵入参量与储层长度成线性关系。储层孔隙度的增加会促进气体的扩散侵入,但这种促进作用非常弱,低孔隙度储层和高孔隙度储层的扩散侵入参量没有数量级的差别。钻井液滤失对气体的扩散侵入具有非常明显的抑制作用,无滤失时的气体扩散侵入参量显著大于滤失时的情况。     

New Proposals of Theoretical Models for Oil Dispersion Concentration in Flow Through a Packed Bed

When a fluid flows through a packed bed, dispersion of fluid occurs as a result of the combined effects of molecular diffusion and mixing in the voids. Thus, in using a packed bed as a coalescer, allowance must be made for the fact that the flow deviates somewhat from plug flow. In general, the dispersion coefficient in the longitudinal direction is greater than in the radial direction. New proposals for theoretical models for dispersion concentration in the packed bed were derived using an analogy between molecular diffusion and flow of secondary dispersion inside the packed bed. A general differential equation has been solved in two directions, the axial and the radial directions, under both unsteady and steady-state conditions.     

New Proposals of Theoretical Models for Oil Dispersion Concentration in Flow Through a Packed Bed

Abstract

When a fluid flows through a packed bed, dispersion of fluid occurs as a result of the combined effects of molecular diffusion and mixing in the voids. Thus, in using a packed bed as a coalescer, allowance must be made for the fact that the flow deviates somewhat from plug flow. In general, the dispersion coefficient in the longitudinal direction is greater than in the radial direction. New proposals for theoretical models for dispersion concentration in the packed bed were derived using an analogy between molecular diffusion and flow of secondary dispersion inside the packed bed. A general differential equation has been solved in two directions, the axial and the radial directions, under both unsteady and steady-state conditions.     

盐酸二甲双胍的平衡溶解度及表观油/水分配系数的测定

建立了紫外分光光度法测定盐酸二甲双胍含量的方法,采用水浴恒温振荡摇瓶法测定盐酸二甲双胍在37℃、不同pH值缓冲液中的平衡溶解度及表观油/水分配系数.结果表明,盐酸二甲双胍在不同pH值下均属于易溶药物;随着pH值升高,盐酸二甲双胍的平衡溶解度增大,而油/水分配系数有减小的趋势,在pH为2.0时的油/水分配系数是pH为8.0时的1.2倍.     

黄原胶发酵过程中流变学行为和气液传质的研究

在10L搅拌式发酵罐中,研究了黄原胶发酵的流变学行为和气液传质特征。发酵液呈现典型的假塑性行为,后期发酵液稠度系数K大于20Pa.snn,流变指数n低于0.2,随着胶浓度的提高,搅拌所带来的剪切力不够,使有效搅拌区域减小,发酵液几乎不随搅拌浆而转动。考察了表观粘度ηm、搅拌转速N和通气速率Ug对体积氧传质系数kLa值的影响,将kLa值与转速N和表观粘度ηm进行了无因次关联。实验条件较高搅拌下的高剪切,不仅能提高整体混合,而且能够促进细胞周边分泌的黄原胶粘液层向主体扩散,有利于强化传递。在所研究的气速范围内,通气速率的提高似乎对气液传质的贡献不大。具有较高剪切和较大有效搅拌区域的反应器被认为更适合于黄原胶发酵过程。     

油水两相流动试井分析方法研究

研究了油水两相流动条件下的压力恢复试井问题。推导出含水饱和度偏微分方程和压力分布偏微分方程;在回归出单井平均相对渗透率曲线的基础上,通过求两个偏微分方程的数值解,求出了径向上的含油饱和度分布、地层渗透率K和平均地层压力;由新引进的变量AD和BD之间的直线关系,求出了井筒存储系数C值。同时,给出了井筒污染系数S值。通过与 Gringarten图版法的解释结果对比,表明本文给出方法的解释结果比较准确可靠。     

正态分布法在油(气)水层判别上的应用

在总结前人应用正态分布法识别油（气）水层的基础上,系统阐述了正态分布法判别油（气）水层的理论基础,并结合某油田测井资料处理解释实例,分析了油（气）层、水层及油水同层的正态分布特征曲线的差异。油层的累计频率正态分布曲线斜率较大,水层的累计频率正态分布曲线斜率较小．油水同层的累计频率正态分布曲线具有分段性,下部较小,上部较大。应用效果表明,正态分布法对于油（气）水层的判别是一种非常实用的方法,具有快速、直观的特点。     

凝析油气相渗曲线测试及对采收率的影响

相渗曲线是描述油气藏渗流中一个非常重要的参数,标准的测定方法是在室温低压下采用模拟油(精制油)模拟气(氮气或空气)来进行测试,未考虑地下高温高压及平衡油气渗流的实际情况。因此,研究高温高压下处于油气相平衡条件(可代表地下实际渗流情况)的两相渗流相渗曲线具有重要的理论和实际意义。本文建立了平衡油气相渗曲线的测试方法,测试了两类流体的平衡油气相渗及其标准油气相渗,并比较了两者之间的差别。将研究结果应用于长岩心定容衰竭实验模拟预测中,能更好地解释长岩心中富含凝析油型凝析气藏凝析油采收率比PVT筒中CVD测试高的实际原因。同时,还发现平衡凝析油气相渗的速敏性,从而说明了适当提高采气速度有利于提高凝析油采收率的观点,对开发技术政策的制订有重要指导意义。     

油水两相流动试井分析方法研究

研究了油水两相流动条件下的压力恢复试井问题,推导出含水饱和度偏微分方程和压力分布偏微分方程,在回归出井平均相对渗透率曲线的基础上,通过求两个偏微分方法的数值解,求出了径向上的含油饱和度分布,地层渗透率K和平均地层压力,由新引进的变量AD和BD之间的直线关系,求出了井筒存储系数C值,同时,给出了井筒污染系数S值,通过与Gringarten图版法的解释结果对比,表明本文给出方法的解释结果比较准确可靠。