塔河油田奥陶系油藏重质烃类堵塞物形成机理及防治方法

塔河缝洞型碳酸盐岩油藏开采过程中有24口井出现沥青质堵塞井筒现象,油井无法生产。实验证明沥青质堵塞物形成的主要原因是凝析油与稠油互相混合作用的结果。结合塔河奥陶系油藏的成藏特征,发现堵塞井均处在凝析气与重油的过渡带上。通过分析生产动态特征,总结了堵塞物形成前后的生产动态变化规律,提出以掺改性稠油为核心的油井解堵、以环空注活性水及地层注水预防沥青质堵塞物形成的综合防治技术,对已出现沥青质堵塞严重的6口井进行了成功的治理,恢复了油井正常生产。

Genetic mechanism and prevention of heavy hydrocarbon stemming in the Ordovician reservoirs of Tahe oilfield

Normal production of 24 oil wells had been interrupted in fractured-vuggy carbonate reservoirs in Tahe oilfield due to blockage of wellbores by bitumen.Lab experiments of bitumen precipitation in mixture of condensate oil and heavy oil show that bitumen stemming is mainly caused by blending of condensate oil and heavy oil.This conclusion with the play characteristics in Tahe oilfield leads to the discovery that blocked wells are all located in the transitional zone from condensate oil to heavy oil.Based on the analysis of production performance,the article sums up the changing pattern of production performance before and after bitumen precipitation and proposes comprehensive prevention methods including blockage removing with addition of modified heavy oil as the core and prevention of bitument precipitation through injecting active water or formation water through annular space.The application of the methods had successfully cured 6 wells and resumed normal production.