注聚井分级注入浓度段塞的现场应用

一直以来,聚合物驱的设计和实施普遍采用＂分阶段、统一段塞＂的注入方式,即同一阶段内,注聚区的所有注入井注相同浓度的聚合物溶液段塞,不同阶段,聚合物溶液的浓度不同。这种方式没有区别各井（区）不同的地层参数,使有的井因黏度太低而仍存在聚合物窜流,而有的井则因黏度太高注不进去。根据孤东油田六区西北部Ng5-6层的注聚过程中暴露出的问题,提出并实施了＂分级注入浓度＂聚合物段塞,井与井之间、同一井的不同时段,其注入段塞也不相同。为了实现这一点,根据流动系数、单井注入压力、吸水指数、启动压力、大孔道分布等5个条件,设计了5种段塞,在不同井、不同时段注入。2008年8月起在六区西北部Ng5-6层的35口井上实施,26口井见效,到2009年4月,比原聚合物驱多增油10190t;在三四区推广实施3个月,也取得明显增油降水效果。

Field Application of Injected Slugs with Various Mass Concentrations in Polymer Injected Wells

All along,the injection way of the polymer flooding is ＂staged slug,unity slug＂ both on the design and implementation commonly.That is were injected into all injected wells in the to say,polymer solution slugs with the same mass concentration area of the polymer flooding at the same stage ,whereas the poly- mer solution slugs with different mass concentrations were injected at different stages.Formation parameters were considered as the same under this injection way.Polymer channeling occurred for much low viscosity in some wells,and the polymer can＇t be injected for much high viscosity in other wells.According to the prob- lems during polymer flooding in Ng5-6 of northwest No.6 area,Gudong Oilfield,＂staged slugs＂ was put forward and implemented,that is to say,different slugs will be injected among different wells and in the same well at different stages.According to the now coefficient,single-well injection pressure,water absorption index,start-up pressure and pore distribution,five kinds of slugs were designed in different wells at different stages. Staged slug has been implemented in 35wells,Ng5-6 of northwest No.6 area since August 2008.Incremental oil production has been 10190t than before in twenty-six wells by the end of April 2009.No.3 and No.4 area have achieved obvious effect of oil increase and water cut decrease after the application for three months.