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

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、3.97 mN/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.