不同数值解法对产水气井压降计算的影响

我国气田气井普遍产水,严重影响气井正常生产。而正确预测产水气井井底压力是对这类气井进行生产动态分析和采气工艺设计的基础。考虑到不同数值计算方法会对产水气井井底压力计算精度和计算时间造成影响,以工程常用的气液两相管流H-B模型为基础,通过实例井对比了采用变管段长度增量形式的迭代法、变压力增量形式的迭代法和龙格库塔法计算井底压力的迭代次数和计算误差,并分析各种数值方法所适用的条件。结果表明,龙格库塔法在较宽压力增量范围内具有最佳的精度,而运算次数与迭代法相当,推荐其为产水气井井筒压降计算数值方法。

The Comparison of Two-phase Flow Pressure Drop Based on Different Numerical Methods

Many gas wells began to produce water in domestic water - gas reservoirs, which severely affected the development of them. So it is important to forecast the partition of two - phase flow pressure gradient in wellbore veritable, which is the foundation of analysis of production performance and technological design of gas production. The different models are used to predict pressure drop, a large error occurs. Therefore, it is necessary, based on the Hagedorn - Brown model, to research the affection in the process of numerical methods changing. On the basis of example, this paper compares the iterative frequency and calculation error of two -phase flow pressure drop based on different numerical methods, and also analyzes the range of application. The results show that Runge - Kutta method had the smallest error to calculate the bottom flowing pressure in inclusive incremental pressure. So we recommend to apply the Runge - Kutta method to forecast the partition of two - phase flow pressure gradient in well- bore.