屏障注水机理研究

Mechanism study of barrier water flooding.

扎纳若尔油田为气顶边水油田 ,在 2 0 0 0年以前主要靠屏障注水方式开发。应用三维三相全组分数值模拟模型研究该油田的屏障注水机理 ,约有 5 6%的屏障注入水进入油环 ,44 %的屏障注入水进入气顶。通过对比屏障注水、2种周期性屏障注水 (注半年、停半年和注 1年、停半年 )、取消屏障注水油环衰竭开发 4种开发效果 ,认为扎纳若尔油田仍有继续采用屏障注水的必要性。为了进一步优化屏障注入水形成水障以后的开采方式 ,对比了油环注水加逐步取消屏障注水 ( 5a内逐步取消 )、油环注水(取消屏障注水 )、油环注水加屏障注水 (油环注水量和屏障注水量分别占总注水量的 85 %和 1 5 % ) 3种开采方式 ,结果表明 :油环注水加屏障注水方式采出程度最高 ,既能保持油环压力 ,又能隔离气顶 ,防止气顶气窜入油井 ,降低油井生产油气比。因而建议扎纳若尔油田的开发方式改为油环面积注水 ,油气界面附近继续屏障注水 ,屏障注水量为保持注采平衡总注水量的 1 5 %左右 ,以维持目前形成水障的稳定性。研究结果对扎纳若尔油田开发调整方案的编制具有指导意义。图 3表

Zanazol is an oil field with edge water and gas cap whose production scheme is primarily barrier water flooding before the year of 2000. This paper studies the mechanism of barrier water flooding with 3 D 3 phase compositional simulator. The result of simulation shows that about 56 percent of barrier injection water was injected into oil ring and 44 percent into gas cap. Through comparing the results of four development schemes which are barrier water flooding, cyclic barrier water flooding (half year for injection and half year for shut in of injectors), cyclic barrier water flooding(one year for injection and half year for shut in of injectors) and natural depletion, it concludes that it is necessary to keep barrier water flooding in Zanazol oil field. In order to optimize the development scheme after barrier wall exists, the following three development schemes are compared: 1) Injecting water into oil ring and gradually stopping barrier water flooding in five year; 2) Injecting water into oil ring (stopping barrier water flooding); 3) Injecting water into oil ring plus barrier water flooding (the water volume injected into oil ring and barrier water injection volume is 85% and 15% of total injected water volume respectively). The simulation result shows that the accumulative recovery of the third production scheme is the highest, this development scheme can maintain reservoir pressure, isolate gas cap, prevent gas in gas cap channeling into producer and thus decrease GOR of producer. It is recommended the production scheme of Zanazol oil field changes to pattern water flooding in the oil ring and continuous barrier water flooding near GOC. To keep the stability of barrier wall developed at present, the water to be injected for barrier water flooding is about 15 percent of the overall water volume necessary to be injected for the balance of injection and production. The research result of mechanism for barrier water flooding is instructive for the accomplishment of the adjustment production plan of Zanazol oil field.