表面活性剂乳化能力差异对低渗油藏提高采收率的影响

表面活性剂驱是低渗透油藏提高采收率的重要技术手段之一,以往筛选活性剂基本以其降低油水界面张力的性能作为评价重点,而表面活性剂的油水乳化性能并未得到足够的重视。为研究油水乳化性能对低渗油藏提高采收率的影响,结合长庆低渗透油藏条件,选用具备相同超低界面张力但乳化能力有所差异的2种活性剂,利用均质、非均质岩心开展驱油实验。实验结果表明:同时具备超低界面张力和强乳化能力的活性剂BA,可在岩心入口段降低渗流阻力,同时实现岩心中部乳化封堵的效果,岩心中部残余阻力系数为2.08;而界面张力超低乳化能力较弱的活性剂TS,无法建立流动阻力,仅起到降压增注的作用。在非均质岩心驱油实验中,水驱后注入BA段塞0.6PV,建立了较高的驱替压力,扩大了波及系数,提高采收率11.46%,而活性剂TS提高采收率幅度为5.88%。

Influence of different emulsifying ability of surfactants on recovery efficiency of low permeability reservoirs

Surfactant flooding is one of the most important techniques for improving recovery of low permeability reservoirs. The performance of the surfactant in reducing oil and water interfacial tension was emphasized in the past, but the emulsifying properties of the surfactant were not paid enough attention. For the study of emulsion performance influence on improving recovery of low permeability reservoirs in this paper, two kinds of surfactants with the same ultra-low interfacial tension and different emulsification ability are selected in combination with the conditions of Changqing oilfield low permeability reservoir, and the experiment of flooding oil displacement is carried out by using homogeneous and non-homogeneous cores. Experimental results show that, with ultra-low interfacial tension and strong emulsifying ability, BA can reduce the seepage resistance in the core entry section and realize the effect of emulsification sealing in the center of the core, the residual resistance coefficient of central core is 2.08. The surfactant TS with ultra-low emulsification ability of interfacial tension can not establish flow resistance, which can only play the role of reducing pressure. In the experiment of the non-homogeneous core, 0.6 PV BA active agent segment, established the displacement pressure, expanded the conformance coefficient, and the recovery rate increased by 11.46%. The recovery rate of the active agent TS was 5.88%.