摘要
针对致密油储层压裂后长时间注水开发效果逐渐变差，注入常规化学药剂难以有效提高采收率的问题，以阴￣非离子型表面活性剂FS￣3、助溶剂ZR￣1和C11—C13直链烷烃为主要原料，研制了一种适合致密油储层渗吸驱油用的纳米流体Nan￣FS，室内评价了其综合性能。结果表明：纳米流体Nan￣FS的粒径范围在10~100 nm，具有良好的分散稳定性；纳米流体Nan￣FS溶液具有良好的界面活性和润湿反转性能，当其质量分数为0.5%时，油水界面张力值降低至10-2 mN/m数量级，并且能使亲油石英片表面的接触角降低至64.5°。纳米流体Nan￣FS溶液还具有良好的渗吸驱油效果，使用质量分数为0.5%的纳米流体作为渗吸液，可使天然岩心静态渗吸150 h后的采收率达到15%以上，而岩心水驱稳定后继续注入0.4 PV纳米流体溶液，可使岩心动态渗吸采收率继续提升25百分点。现场试验结果表明，M区块内5口采油井采取注纳米流体Nan￣FS渗吸驱油措施后，平均日产油量明显提升，平均含水率明显降低，达到了良好的降水增油效果。
Abstract
Aiming at the problem that the water injection development effect of tight oil reservoir becomes worse after fracturing for a long time and the injection of conventional chemicals difficult to effectively improve its oil recovery, a nanofluid Nan￣FS suitable for tight oil reservoir imbibition and oil displacement was developed with anionic non-ionic surfactant FS￣3, cosolvent ZR￣1 and C11￣C13 linear alkanes as the main raw materials, and its comprehensive performance was evaluated in the laboratory. The results show that the particle size of nanofluid Nan￣FS ranges from 10 to 100 nm and has good dispersion stability. Nanofluid Nan￣FS solution has good interfacial activity and wetting reversal performance. When the mass fraction is 0.5%, the oil-water interfacial tension can be reduced to the order of 10-2 mN/m, and the contact angle on the surface of lipophilic quartz sheet can be reduced to 64.5°. Nanofluid Nan￣FS solution also has good imbibition and oil displacement effect. Using nanofluid with mass fraction of 0.5% as imbibition fluid can make the recovery of natural core reach more than 15% after static imbibition for 150 h. After core water drive is stable, continue to inject 0.4 PV nanofluid solution, which can continue to improve the dynamic imbibition recovery of core by more than 25 percentage points. The field test results show that, after using imbibition and oil displacement measures of injecting nanofluid Nan￣FS for the five oil wells in block M, the average daily oil production is significantly increased, the average water cut is significantly reduced, and a good effect of water cut decrease and oil increase is achieved.
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