相态变化影响下的凝析气井井筒压力变化计算分析

Calculation on change in borehole pressure of gas condensate well at the condition of phase change

凝析气井在开发生产过程中具有特殊的相态变化特性,当井筒中整个流体体系压力达到露点压力以后,凝析液不断析出导致液相含量不断增加。以往对凝析气井井筒动态模拟过程中几乎没有考虑到,这样难以保证模拟的精确度。因此,建立了凝析井井筒压力、流体相态变化计算的分析模型,计算和分析了井筒中气液两相中组分含量不断变化的过程,考虑到了相态变化对井筒压力分布的影响。引入气油比增量比的一种新参数,对井筒中不同井段凝析油的析出程度进行了直观描述。并改变重组分含量进行不同组分下气、液两相的相态变化计算。综合分析了不同组分对井筒压力梯度的动态影响,使得模拟和计算更加接近于真实情况。

Gas condensate well has special characteristics of phase change in production process.When the whole fluid system pressure attained dew point pressure,condensate fluid drops out continuously,causing liquid content increase.In the past there was almost no such consideration in the process of dynamic simulation of gas condensate wellbore,so it is difficult to guarantee accuracy of simulation.This paper establishes analytic models of gas condensate well bore pressure and fluid phase change,calculates and analyzes component change of gas and liquid phases,and considers effect of phase change on wellbore pressure.It uses a new parameter of incremental ratio of gas/oil ratio,which describes separation of condensate oil in different section of wellbore.And calculates on phase change of gas and liquid phases by changing in heavy component content.It analyzes dynamic effect of different components on wellbore gradient so as to make simulation and calculation more close to the situation.