断层封闭性在油田开发中的应用

Application of fault-sealing in oilfield development

以大港复杂断块油田为例,提出了油田开发过程中断层封闭性的研究思路与方法。通过利用静态、油藏工程、数值模拟及现场动态测试相结合的方式,判定断层是否具有封闭性或有无后期活化现象。首先,通过静态方法识别断层,然后利用油藏工程、现场测试等方法分析断块是否封闭,以及寻找不密封断层,最终依据剩余油的分布状况,确定合理注采比例,调整注采井网形式,提高油藏水驱控制程度。在此基础上,提出要控制断层附近注水井的注入压力和注水量,避免断层后期活化,以便达到减少无效注水、减缓油水井套变及充分挖掘油藏潜力之目的。ZY油田部分断块断层封闭性较差,针对周围生产井受益不明显的井,注水外溢量大于75%的注水井,采取了转采方式或停注的措施对策。通过相应对策的实施,较大程度地提高了开发中后期老油田的经济效益。

Taking Dagang Oilfield as an example, the paper puts forward the idea and method of fault-sealing research during oilfield development. The combination of static method, reservoir engineering, numerical simulation and site testing is used to determine whether the fault is sealed or active. First of all, the faults are identified by static state method. Then reservoir engineering and site testing methods are applied to judge fault sealing and find non-sealed fault. After that, the reasonable proportion of injection-production is determined, and the injection-production well pattern is adjusted according to the distribution situation of residual oil. So the controlling degree of water flooding could be improved. For the injection wells near the faults, the injection pressure and injection rate should be controlled to avoid the late activation of the fault in order to reduce ineffective water injection, slow down casing deformation and exploiting the potential of this kind of reservoir sufficiently. In ZY Oilfield, the fault closure in part of the fault blocks is poor and the producers around are not benefited obviously, so the wells with overflow volume in the injection over 75% need to be converted or shut down. It was recommended that Hz should be taken in the top depth for one-layer pay and the mid-to-top depth for muhi-layer zones about the injectors near the faults, and rupture probability X should be 10-15%. Through the implementation of the above the measures, economic efficiency of the old oilfields is improved greatly during middlelate development period.