涩北气田连续油管冲砂作业分析

An analysis of coiled tubing sand washing operation in the Sebei gas field

涩北气田生产过程中极易出砂,要恢复气井正常生产,就要将砂冲出来,解放产层。由于地层压力低,常规冲砂方法容易使地层压漏,返排困难,对气层造成严重的污染,达不到提高产量的目的。在使用连续油管进行了10口井冲砂作业的基础上,通过对典型井的分析,认为冲砂作业成功的关键是合理控制冲砂排量、井口油压(回压)、泵液时间、泵液量、冲砂速度等,使井口油压、液柱压力、砂柱压力、气柱压力、油管与连续油管环空间的循环阻力之和小于井底地层压力,让产层中的天然气不断地流入井筒,达到减少地层污染的目的。实验结果对今后涩北气田进行大规模的连续油管冲砂作业具有指导作用。

Sanding occurs easily during the production process in the Sebei gas field,so the sand must be washed out to release producing layers for resuming the normal production of a gas well.Due to low formation pressure,conventional sand-washing methods can easily cause formation pressure leakage,difficult reverse discharging and severe damage to formation,hardly achieving the purpose of improving production.After sand washing operation being carried out for 10 wells by using coiled tubing,the analysis of typical wells shows that the key to the sand-washing operation is to rationally control sand-washing displacement,wellhead pressure,pump fluid time,pump fluid volume and sand-washing speed to make the pressure sum of wellhead pressure,fluid/sand/gas column pressures and circulation pressure between tubing and coiled tubing annulus lower than bottom-hole formation pressure to let natural gas flow into shaft continuously,achieving the purpose of reducing formation damage.The study in this paper is of great guiding significance for the large scale coiled tubing sand washing operation of the Sebei gas field in the future.