涩北气田排水采气优选模式

The optimal method selection for dewatering production at Sebei gas field

针对柴达木盆地涩北气田所面临的气井井底积液、产水导致产量迅速递减的问题,从准确把握气井排水采气时机、优选经济有效的排水采气方式出发,结合涩北气田生产动态,综合考虑动能因子、积液高度、油压、日产水以及油压、套压压差等多种因素准确诊断了气井积液的状况;分析了涩北一号气田递减阶段气井日产气量和水气比等生产数据的变化规律,根据多项管流井底压力计算理论、临界流量计算模型及涩北气田实际的采气油管尺寸,研制出了排水采气方式选择控制图,并建立了涩北气田排水采气优选模式;回归出了相应的计算公式,预测了涩北一号气田大规模进入优选管柱排水及泡排排水采气时期的具体时机,由于涩北气田属于次活跃与不活跃水驱气藏,水气比上升缓慢,除少数离边水比较近的井外,在整个开发期内不会大规模进入气举排水开采期。

The bottom hole liquid loading and water production in Sebei gas wells at the Qaidam basin have resulted in sharp quick decrease in production.To accurately diagnose this situation,a research is made on many factors of bottom hole liquid loading,such as kinetic energy factor,liquid loading height,wellhead pressure,daily water production,and tubing pressure/casing pressure differential,etc.Then by taking into consideration of the inflow performance of the Sebei gas field and based on the research,a control chart for the selection of drainage gas recovery method is developed and an analysis is made on the variation rules of the daily gas production and gas/water ratio of the Sebei-1 gas field during production-declining period.And by using the multi-phase pipe flow BHP calculation theory,the critical flow rate calculation model and the actual sizes of gas production tubings used at the Sebei gas field,a control chart is developed for the selection of optimal drainage method for gas production.Finally an optimization model is established.And the corresponding calculation formula is obtained through regression.The timing for large-scale drainage with optimal string configuration and foam at the Sebei-1 gas field is predicted too.Because the Seibei gas field is a less active and not active water-driving gas reservoir,the water/gas ratio increases very slowly,there will be no large-scale gas-lift drainage during the development phase except in a few wells close to the edge water.