基于反凝析特性的凝析气井生产优化分析

PRODUCTION-OPTIMIZING ANALYSIS OF GAS CONDENSATE WELL WITH RETROGRADE CONDENSATE PROPERTY

凝析气井在生产中常常会出现反凝析液析出的特殊现象 ,单井生产系统因而表现出与常规气井不同的生产特性。凝析气井生产系统优化分析的关键问题在于如何将反凝析特性反映进生产优化过程。文章提出了以防止储层出现反凝析液析出并避免气井积液为凝析气井生产优化目标 ,认为生产系统优化应根据井底流动状态分别考虑 ;引入了两相拟压力函数来建立气液两相流入动态方程 ,能够准确地描述凝析液对储层渗流的动态影响 ,而常规单相气或修正方法往往是高估或低估了气井无阻流量 ;在井筒流动模型中考虑了凝析气相态变化影响 ,与常规多相流或拟单相流模型进行了对比分析 ,结果表明考虑气液相变的多相流模型有助于正确分析井筒流动状态。利用提出的优化分析方法进行了程序设计 ,并对两口凝析气井进行了实例分析 ,结果表明文章提出的优化分析方法有助于正确制定凝析气井合理工作制度 ,从而确保单井在最佳状态下生产。

A special phenomenon of releasing retrograde condensate liquid is always found in the producing process of gas condensate well, so that the single well production system showed up the characteristics different from the conventional gas well. The key to the production-optimizing analysis of the gas condensate well lies in how to make the retrograde condensate property be brought in the production-optimizing process. In the paper, the production-optimizing target for preventing the retrograde condensate liquid from being released into the reservoir and accumulated in the gas well is proposed and it is thought that the production system optimization should be considered respectively in light of bottom-hole flow states. Through introducing the pseudo-pressure function to the tow-phase (gas-liquid) inflow dynamic equation, the kinetic influence of the retrograde condensate liquid on the percolation flow in the reservoir could be exactly described, however, the gas well open-flow capacity was over-valued or under-valued by the conventional single-phase gas or modified method. The effects of the change in phase states were considered in the well bore flowing model. In comparison with the conventional multiple-phase flow or pseudo single-phase flow model, the result shows that the multiple-phase flow model in consideration of gas-liquid phase change is conducive to correctly analyzing well bore flow states. The program design was carried out by use of the optimizing analysis method proposed in the paper and two gas condensate wells were actually analyzed by the authors. It is indicated that this method can make a contribution to correctly drawing up reasonable working systems for the gas condensate wells, thus ensuring the individual well's being put production under the optimal conditions.