均质致密油藏表面活性剂驱油效率研究

Study on Surfactant Flooding Efficiency of Homogeneous Tight Oil Reservoirs

W油藏为超低渗油藏,储层非均质性强,注水开发效果不明显,基于此开展了表面活性剂驱油研究。通过室内物理模拟驱油实验对驱油体系的性能和影响效率因素进行研究。实验结果表明:KPS+CDEA 1∶1复配体系,其与原油的界面张力值为10^(-4) mN·m^(-1)数量级,体系具有良好的耐温抗盐性,60天后界面张力仍能达到3.27×10^(-3) mN·m^(-1);在实验质量分数范围内,体系质量分数对乳液类型无明显影响,均为O/W型,乳液的稳定性随体系质量分数增加而提高;复配体系与原油形成的乳液粒径平均在2.39μm左右,与油藏的孔喉直径有良好的匹配性;室内物理模拟实验表明,采收率增值与降压率均随界面张力的降低而逐渐提高。在均质条件下,复配体系在0.15 mL·min^(-1)的注入速度与0.6 PV的注入段塞体积时驱油效果最佳。该体系在降压增注的同时也能提高油的驱油效率,这对超低渗油藏的开发具有重要意义。

The W reservoir is an ultra-low permeability reservoir with strong reservoir inhomogeneity and insignificant water injection development effect.In this paper,the research on surfactant oil drive was carried out.The performance of the oil drive system and the factors affecting the efficiency were investigated through indoor physical simulation oil drive experiments.The experimental results showed that the interfacial tension value of KPS+CDEA1:1 complex system with crude oil was 10^(-4) mN·m^(-1) order of magnitude,and the system had good temperature and salt resistance,and the interfacial tension still reached 3.27×10^(-3) mN·m^(-1) after 60 days.The particle size of the emulsion formed by the compound system and the crude oil was about 2.39μm on average,which had a good match with the pore throat diameter of the reservoir.The indoor physical simulation experiments showed that the added recovery rate and the pressure reduction rate both increased gradually with the decrease of interfacial tension.Under the homogeneous condition,the best oil repelling effect was achieved with the injection rate of 0.15 mL·min^(-1) and the volume of 0.6 PV of the injected section plug.This system could improve the oil drive efficiency while lowering pressure and increasing injection,which is important for the development of ultra-low permeability reservoirs.