大港油田港东二区四五断块聚合物注采实践

Practice of polymer injection and production in the 4th and 5th Fault Blocks of Gangdong 2nd Block in Dagang Oilfield

由于多年的注水开发,大港油田港东开发二区四五断块已进入高含水高采出程度开发后期,主力砂体水淹严重,一类储集层大多进入高含水或特高含水期,加之储集层非均质性严重,各层吸水量差异大,油层动用程度较低,剩余油高度分散,区块井网部署、措施挖潜难度加大。进一步提高区块采收率,增油降含水,是开展此次聚合物实践的目的。在剩余油高度分散的聚驱后期,精确地质认识,选择合理的开发层系,科学调整井网,是注聚见效的基础;优化注采速度、保证聚合物均衡驱替,是注聚见效的保证,对提高注聚效果、进一步提高区块采收率至关重要。通过在港东开发二区四五断块实施后,产量实现翻番,由123 t/d上升至256 t/d,并稳产8个月,综合含水率下降2%,预测聚驱相对水驱提高采收率12.8%,取得了良好的效果。

Due to years of water flooding extraction,the 4th and 5th Fault Blocks of Gangdong 2nd Block in Dagang Oilfield have entered late in development with high water cut and high recovery.The main sand bodies are heavily flooded,and most of the reservoirs with good quality have entered high water cut and ultra high water cut period.Besides,the serious heterogeneity of the reservoir and the great difference in water absorption between each layers cause low utilization of oil layers.Highly dispersed remaining oil makes it more difficult to deploy well patterns in the block and conduct potential tapping measures.This polymer practice is carried out with a view to further improve recovery efficiency in the block,and increase oil production and reduce water cut.In the late stage of polymer flooding where remaining oil is highly dispersed,accurate geological understanding,reasonable development of strata,and scientific adjustment of well patterns are the basis for effective polymer injection.Optimization of injection and production speed and balanced displacement of polymer are the guarantee for effective polymer injection,which is crucial to the improvement of polymer injection effect and recovery efficiency.After implementation in the 4th and 5th Fault Blocks in Gangdong 2nd Block,the output doubled from 123 t/d to 256 t/d.Good effect is obtained with stable production for 8 months,comprehensive water cut decreased by 2%,and predicted recovery efficiency increased 12.8%by polymer flooding relative to water flooding.