烷基羧酸甜菜碱驱油机理研究

Study on oil displacement mechanism of alkyl carboxyl betaine

为了探究不同甜菜碱的微观驱油机理,文章选取三种具有不同疏水烷基链长度的羧酸甜菜碱表面活性剂进行微观可视化驱油实验,并测定了界面张力和乳化性能。实验结果表明,烷基羧酸甜菜碱能够高效降低油水界面张力,促进原油原位乳化。随着烷基链长增加,界面张力进一步降低,乳化效果增强。十六烷基羧酸甜菜碱提高采收率机制包括以下两个方面:0.3%C16BC可以将界面张力降至10^(-2)mN/m数量级,通过乳化和弱剪切作用有效启动孔道中原油,将柱状、多孔和簇状剩余油分解形成水包油乳化油滴,提高洗油效率。同时,由于乳化油滴产生的贾敏效应叠加,C16BC可产生稳定的堵塞通道效果,使残余油的水相波及效率提高了20%。C16BC作为一种可以原位乳化协同自调剖的驱油剂,驱油效率较地层水驱提高42%以上,可以用于低渗油藏化学驱提高采收率。

To explore the oil displacement mechanism of betaine surfactants,three alkyl carboxyl betaines with different alkyl chain lengths were selected for microscopic visualization oil displacement experiments.The oil-water interfacial tension(IFT)and the emulsification of crude oil were also measured.The experimental results showed that alkyl carboxyl betaines could effectively reduce the IFT and promote the in-situ emulsification of crude oil.With the increase of alkyl chain length,the IFT decreased and the emulsifying effect was enhanced.The mechanism of enhanced oil recovery by cetyl carboxyl betaine(C16BC)included the following two aspects:0.3%C16BC could reduce the IFT to the order of magnitude of 10^(-2) mN/m,effectively mobilize the crude oil in the pores through emulsification under weak shear,and break the columnar,porous and cluster remaining oil into oil droplets by formation of oil-in-water emulsion,which improved the oil washing efficiency.At the same time,due to the superposition of the Jamin effect generated by emulsified oil droplets,C16BC could stably produce a channel blockage effect,which increased the sweep efficiency by 20%.As an oil displacement agent exhibiting in-situ emulsification synergistic self-profile control,the oil displacement efficiency of C16BC was 42.1%higher than that of formation water flooding,which could be used to improve the recovery of chemical flooding in low-permeability reservoirs.