考虑气液比影响的原油采输流场等效剪切速率计算方法

Equivalent Shear Rate Calculation Method in the Flow Field of Crude Oil Production and Transportation Considering the Influence of Gas-Liquid Ratio

紊流剪切是原油采输系统普遍存在的流动特征,其剪切效应的等效模拟一直是油水乳化及多相流动研究中面临的一项难题。基于对剪切流场的物理描述,以油井井筒区域和井口油嘴区域为研究对象,考虑原油采输过程中含水率及气液比变化工况,结合对流场特性的数值模拟,构建了流场等效剪切速率计算方法。该方法的实例计算结果表明,流场等效剪切速率受含水率影响不明显,在相同含水率工况下,流场的等效剪切速率随着气液比的增加而增大;含水率为80%的工况下,气液比从240:1增加到430:1时,等效剪切速率在油井井筒区域和井口油嘴区域增幅分别达到84%和76%。研究结果为原油采输系统相关研究中油水乳化液体系的模拟制备及多相流动相似性模拟提供了必要的理论基础。

Turbulent shear is a common flow characteristic in the production and transportation system of crude oil. The equivalent simulation of its shearing effect is always a difficult problem in the study of oil-water emulsion and multiphase flow. Based on the physical description of shear flow field,the wellbore and wellhead choke are taken as the objects to study. Considering the water cut and gas liquid ratio change in the process of crude oil production and transportation, and combined with the numerical simulation of flow field characteristics, the calculation method of flow field equivalent shear rate is determined. The example calculation results indicate that the equivalent shear rate of flow field is not obviously affected by water cut,and the equivalent shear rate of flow field raises with the gas liquid ratio increasing under the same water cut condition. When the water cut is 80% and the gas- liquid ratio increases from 240:1 to 430:1, the equivalent shear rate increases by 84% and 76% in the wellbore and wellhead choke area respectively. The study results provide the necessary theoretical basis for simulation preparation of oil- water emulsion system and similarity simulation of multiphase flow in the study of crude oil production and transportation system.