准确预测持液率可为井筒中的流型判断和压降预测提供重要依据,段塞流为稠油井筒中最常见流型,井筒高黏流体将加重气液两相滑脱,导致现有持液率模型应用于高黏流体的预测精度变差。为此,基于多相管流实验平台,在内径为60 mm的测试管段内开展段塞流持液率实验,获取了不同黏度、不同倾角段塞流流型及持液率数据,研究了黏度对持液率和流型转变的影响规律,并结合实验现象和理论推导,提出了倾斜管不同黏度气液两相段塞流持液率新模型。研究结果表明:液相黏度的增加,会增加液相与管壁之间的黏滞力,导致持液率增加;黏度对持液率的影响会改变段塞流与其他流型的转变界限。以Kora液塞区持液率关系式为基础,建立了用混相黏度代替液相黏度的倾斜管气液两相段塞流持液率新模型,并利用实验数据和文献数据进行了验证,证实新模型具有更高的精度。该研究可为预测稠油井井筒压降提供技术支持。
Accurate prediction of liquid holdup provides important basis for flow pattern identification and pressure drop calculation in wellbores. Slug flow is the most common flow pattern in heavy oil wellbores. High-viscosity fluids in the wellbore will exacerbate gas-liquid two-phase slippage, resulting in poor prediction accuracy of existing holdup models applied to high-viscosity fluids. Therefore, a new model for liquid holdup in gas-liquid two-phase slug flow in inclined pipes with different viscosities is proposed. This proposal is based on experimental observations and theoretical derivations. The holdup experiments of slug flow are conducted in a multiple phase pipe flow experimental platform, in a test string with an inner diameter of 60 mm. The influence of viscosity on liquid holdup and flow pattern transitions is studied based on the data of slug flow patterns and liquid holdup obtained with different viscosities and different inclinations in the experiments. The study shows that an increase in liquid viscosity will intensify the viscous resistance between the liquid phase and the pipe wall, resulting in a rise in liquid holdup. While the effect of viscosity on liquid holdup will change the transition boundaries between slug flow and other flow patterns. A new model for liquid holdup in gas-liquid two-phase slug flow in inclined pipes is established. This model is based on the Kora liquid holdup relationship formula and uses mixed-phase viscosity instead of liquid-phase viscosity. The model is validated by experimental and literature data, with confirmed higher accuracy. This research can provide technical support for predicting pressure drop in heavy oil wellbores.
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