纳米沸石咪唑酯骨架颗粒性能评价与驱油效果

Performance Evaluation and Oil Displacement Efficiency of Zeolitic Imidazolate Framework Nanoparticle

何旋 刘月田 柴汝宽

HE Xuan，LIU Yuetian，CHAI Rukuan

为分析纳米沸石咪唑酯骨架（ZIF）颗粒作为纳米驱油剂对提高原油采收率的作用，以六水合硝酸锌、2-甲基咪唑为原料，在室温与水相条件下制备了纳米ZIF-8 颗粒。对其微观结构进行了表征；将纳米ZIF-8 颗粒分散在水中得到纳米流体，研究了该流体的稳定性，通过测定油水界面张力和接触角分析其提高采收率机理；最后通 过岩心驱替实验评价了纳米ZIF-8 驱油体系的驱油效率。结果表明，纳米ZIF-8 颗粒的平均直径为65.8 nm，相态单一无杂质；当加量不高于0.03%时，纳米ZIF-8 颗粒在水中的分散性良好，Zeta 电位绝对值约30 mV，具有较高的稳定性。在模拟地层水和低矿化度水中添加0.03%的纳米ZIF-8 颗粒，油水界面张力值分别降至4.66、3.97mN/m，比未添加时降低了75.77%、73.25%；纳米流体在岩心切片表面的接触角分别由114°、109°降至78°、73°，岩石表面润湿性转为水湿，更有利于油膜的剥离。岩心驱替实验中，用地层水驱替至无油产出后转注0.03%的纳米ZIF-8流体，在地层水和低矿化度水中的采收率分别提高8.25百分点、10.7百分点，提高采收率效果较好。

In order to analyze the effect of zeolitic imidazolate framework（ZIF）nanoparticles as nano-oil flooding agent on enhanced oil recovery，ZIF-8 nanoparticles were prepared at ambient temperature and aqueous phase using zinc nitrate hexahydrate and 2-methylimidazole as original materials. The microstructure of ZIF-8 nanoparticles was characterized. ZIF-8 nanoparticles were dispersed in water to obtain nanofluid. The stability of the nanofluid was studied，and the mechanism of enhanced oil recovery was analyzed by measuring oil-water interfacial tension and contact angle. Finally，the oil displacement efficiency of ZIF-8 oil displacement system was evaluated through core displacement experiment. The results showed that the average diameter of ZIF-8 nanoparticle was 65.8 nm，and the phase state was single without impurity. When the mass fraction was not higher than 0.03%，the dispersion of ZIF-8 nanoparticle in water was excellent，and the absolute value of Zeta potential was about 30 mV，indicating a high stability. After adding 0.03% ZIF-8 nanoparticle to simulated formation water and low salinity water，the oil-water interfacial tension decreased to 4.66 and 3.97 mN/m，respectively，which decreased by 75.77% and 73.25% compared with that without adding. The contact angle between nanofluid and core slice decreased from 114° and 109° to 78° and 73°，respectively，and the rock surface turned to water-wet，which was more conducive to the peeling of oil film. In the core displacement experiment，after flooding with formation water until oil-free production，0.03% ZIF-8 nanofluid was injected. The recovery factor in formation water and low salinity water was increased by 8.25 percentage points and 10.7 percentage points，respectively，which showed a good effect of enhanced oil recovery.

10.19346/j.cnki.1000-4092.2022.02.022