基于垂直管道内重油-水两相流动型态的持水率和压降预测模型

Prediction Models of Holdup and Pressure Gradient Based on Heavy Oil-water Flow Patterns in Vertical Pipe

针对重油井筒举升流动规律认识不清的问题,采用高黏重油作为研究对象,研究重油-水在上升管中的流动特性,得到了五种重油-水两相流动型态。结果表明:与轻油-水流动不同,重油-水流动过程中未发生相转化,该现象与表面能方程的预测结果相似。通过持水率测量得到重油-水两相的滑移效应随油水混合流速降低或持水率增加而变得更加明显,基于漂移流模型和动量守恒方程推导得到五种流态下重油-水两相流的持水率预测模型,相对误差率在20%以内。总压降梯度在低持水率时以重力压力梯度为主,高混合流速和高持水率时以摩擦压力梯度为主。采用基于Bannwart模型建立的重油-水中心环状流压降预测模型,误差率在30%以内。研究结果为进一步提高重油井筒举升流动参数的预测精度提供了理论基础。

Aiming at the problem of unclear understanding for heavy oil flow during lifting in wellbore,heavy oil with high viscosity was used to study the flow characteristics of heavy oil-water in upward pipe.All the flow patterns identified can be grouped into five flow categories.Unlike low-density oil-water flow,phase inversion of heavy oil-water did not occur which was in agreement with a surface energy equation.Slippage effect which was evaluated by water holdup measurements tends to be more significant with decreasing mixture velocity or increasing input water fraction.The flow pattern-based modified drift-flux models and momentum equations proposed in the current study performed well on water holdup prediction,the error rate was less than 20%.Lastly,the total pressure gradient was found to be gravity dominant at low water holdup while be friction dominant at high mixture velocity or high-water holdup.The pressure gradient prediction model of heavy oil-water central annular flow based on Bannwart model was established,and the error rate was less than 30%.A theoretical basis is provided for further improving the prediction accuracy of flow parameters during heavy oil lifting in wellbore.