【作者】 张敏革；

【导师】 李鑫钢；

【作者基本信息】 天津大学 ， 化学工程， 2009， 博士

【摘要】 随着超高分子量部分水解聚丙烯酰胺(HPAM)溶液在我国三次采油技术中的广泛应用,聚合物驱配制工艺中的熟化单元成为制约采油工程正常运行的关键。对熟化单元中的HPAM溶液流变行为、搅拌装置混合性能以及HPAM溶液搅拌流场特性进行研究成为一项迫切需要深入研究的课题。为从微观上加深对驱油用HPAM的认识,借助于Brookhaven多角度激光散射仪对HPAM分子微观流体力学半径分布进行了测量。HPAM分子量越高,平均流体力学半径也越大;为全面考察HPAM溶液的流变行为,采用HAAKE Rheostress 150流变仪对HPAM溶液进行了稳态剪切流变性和小振幅动态振荡剪切流变性研究。结果发现,聚合物溶液的弹性能量非常显著,表观粘度具有剪切稀化的性质;在相同分子量下,聚合物溶液的浓度越高,其表观粘度、第一法向应力差、弹性模量和粘性模量越大。根据HPAM溶液的流变特征,得到了能够满意表征HPAM溶液的粘弹性本构方程-KBKZ本构方程。在方程参数确定过程中,提出了一种通过构造目标函数,采用非线性规划方法求极值点的一步法求解全部模型参数的方法。并通过合理简化,降低了KBKZ本构方程松弛时间谱个数。为全面考察适合于聚合物熟化搅拌装置-双螺带螺杆搅拌桨的混合性能,采用多重参考系法对这种搅拌桨在牛顿流体、非牛顿流体、气-液两相和固-液两相流中的搅拌流场进行了数值模拟研究。结果发现,双螺带螺杆搅拌桨能使流体在槽内产生轴向大循环;流体剪切稀化性质越显著,搅拌槽内无因次速度及循环量数均有不同程度的降低。双螺带螺杆桨对搅拌槽内气-液两相流体的气相具有汇聚和排出作用;在搅拌固-液两相流时,搅拌槽底部中间及槽底部边缘易形成死角,改型后的双螺带螺杆-锚式组合桨一定程度上改善了固液混合状况。采用粒子成像测速(PIV)技术对HPAM溶液搅拌流场进行了研究,发现双螺带螺杆桨在粘弹性流体中的搅拌流场呈现轴向大循环的特征。溶液的弹性使槽内流体的平均速度和平均剪切速率有所降低。本文研究结果不仅对三次采油聚合物地面配制工程具有重要的实用价值和理论意义,同时对聚合物溶液流变性本质、流体混合机理等基础性研究具有一定的现实意义。更多还原

【Abstract】 With the widespread application of partial hydrolyzed polyacrylamide (HPAM) solution with ultrahigh molecular weight in the tertiary recovery technology in China, the maturation unit, one process in the preparation of polymer flooding, has become the critical step in the regular operations of oil recovery engineering, which lead to the rheological behavior of HPAM solutions, mixing performance of the stirring apparatus, as well as the HPAM solution flow field in maturation tank need to be further studied.In order to understanding the microscopic properties of HPAM, the hydromechanical radius distribution of HPAM molecular were measured by using Brookhaven laser scattering apparatus. It is found that the higher the molecular weight of HPAM is, the lager the average hydromechanical radius is. Overall investigations on the rheological behavior of HPAM solutions with different concentrations and molecular weights were conducted by means of HAAKE Rheostress 150 rheometer under the scan modes of steady shear flow and dynamic oscillation shear flow. It is shown that, the polymer solutions have significant elastic energy and the apparent viscosity exhibit shear thinning behavior. At the same molecular weight, the apparent viscosity, first normal stress difference, elastic modulus and viscous modulus increase with increasing polymer solution concentration.According to the rheological characteristics of HPAM solutions obtained from experiments, the KBKZ constitutive model was achieved to describe the viscoelastic properties of the polymer solutions, In the process of determining model parameters, a novel method, which can solve all the model parameters using one step by minimizing a established objective function with the principle of nonlinear programming method, was proposed. Through proper simplification, the relaxation time spectrums in the KBKZ equation were reduced.To comprehensively investigate the mixing performance of double helical ribbon and screw impeller, which is suitable for mixing polymer solutions, three dimensional numerical simulation for Newtonian, non-Newtonian fluid, gas-liquid and solid-liquid two phase flow fields generated by this impeller were conducted by using multiple reference frames impeller method. The results show that, the double helical ribbon and screw impeller makes fluid in stirred tank form large axial circulation. The more significant shear thinning properties the fluid have, the lower normalized axial velocity and circulation number in the flow field. The double helical ribbon and screw impeller plays a role to converge and discharge gas for the gas-liquid flow in the stirred tank. However, when the impeller agitates the solid-liquid fluid flow, it is easy to form retention in the central and circumferential region on the bottom of stirred tank. In this case, a combined double helical ribbon screw and anchor agitator has been developed to improve the mixing effect .The HPAM solution flow field stirred by double helical ribbon and screw impeller in stirred tank were measured by particle image velocimeter (PIV), it is found that, there is a great axial circulation in the viscoelastic fluid flow field. Because of the elastic properties of the HPAM solutions, the average velocity and average shear rate in the flow field, to some extent, have been declined.The results of the present work give practical and theoretical values for the polymer solution preparation above ground in enhanced oil recovery engineering, it also help to deeply understand the rheological nature of the polymer solution and the mixing mechanisms of the mechanically agitated tank.更多还原