井筒特殊流态对气井积液影响的新认识

NEW UNDERSTANDING OF EFFECT OF PARTICULAR FLOW REGIME IN BOREHOLE ON LIQUID LOADING IN GAS WELL

在产水气井生产中，井筒积液是一个严重的问题。当气井产量下降，气体流速低于临界携液流速时，气井井筒就会发生积液。气体无法把产出水全部携带出井筒，水会回落到井底并聚集成液柱，堵塞炮眼，增加气藏回压，急剧降低气体流速，导致气井产量大幅度下降或是将气井压死。通过对国内外油田产水气井动态资料的分析研究得出，气井生产可分为两个主要时期：①气井开采初期，气体的稳定流动过程；②井筒积液后，气体的亚稳态流动过程。引出了亚稳态流动理论模型，通过对井底条件的假设，详细地介绍了气水同产、凝析水回落聚集成液柱和部分液体回注入储层的循环流动过程。论点的提出为描述井筒积液的过程提供了新的思路，可为间歇气井的生产优化过程提供理论帮助。

Liquid loading is a serious problem of gas producers with water production. It occurs in gas producers when production of gas producers decreases and gas flow velocity is lower than critical liquid-carrying velocity. Gas can not carry all produced water out of well, and water will fall back to bottom hole and accumulate a liquid column. Therefore, perforations will be plugged, back pressure of gas reservoirs will increase, and gas flow rate will decline sharply, causing production from gas producers to decline greatly, or gas producers will not be able to flow. Study on dynamic data from gas producers with water production of oilfields at home and abroad shows that gas well production can be divided into two periods：①stable gas flow process at the early production stage;②metastable gas flow process since liquid loading. This paper gives a theoretical model for the metastable flow and presents a circulating flow process, in which gas and water are produced simultaneously, condensate falls back and accumulates into a liquid column, and part of liquid is injected into reservoir, by assuming bottom hole conditions. This theory provides a new thought for describing liquid loading process and gives a theoretical help for production optimization process of intermittent gas producers.