低渗透油藏微乳液驱油提高采收率机理研究

发布时间：2018-12-14 14:12

【摘要】：本文分别利用十二烷基硫酸钠、十二烷基甜菜碱、吐温-20作为表面活性剂,正丁醇作为助表面活性剂,制备了不同体系的微乳液体系,并测定其界面张力、粒度分布曲线、粘度和稳定性等参数。选用十二烷基甜菜碱配制成的微乳液进行物理模拟实验,以大庆油田低渗透岩心为实验对象,进行启动压力梯度测定、相对渗透率曲线测定、光刻玻璃模型剩余油研究实验、微乳液驱油实验和岩心微观解剖实验,从不同角度分析了微乳液提高采收率的机理。微乳液中的表面活性剂可以吸附在岩石表面,大幅度降低固-液界面张力,减小了边界层流体流动的渗流阻力,使细小孔隙中的流体在较小的驱替压差下就可以克服粘附力而参与流动。同时,离子型表面活性剂可以解离出一定量的电荷,这些电荷可以吸附在边界层流体的表面,压缩扩散双电层,从而降低了边界层的厚度,增大了孔隙的实际过流面积。因此,微乳液体系可以大大降低岩心的启动压力梯度,减小渗流过程中的阻力。油水界面张力的降低使油滴的变形更加容易,削弱了贾敏效应产生的附加阻力,使油相的相对渗透率显著增加,并降低了残余油饱和度。微乳液对油滴状剩余油和膜状剩余油的驱替效果最好,而对盲端状剩余油的驱替效果最差。喉道半径和孔喉比是影响微乳液驱油效果的最主要因素。微乳液能够降低油水界面张力和启动压力梯度、改善油水流度比,因此能够大幅度提高原油采收率。
[Abstract]:Using sodium dodecyl sulfate, dodecyl betaine, tween-20 as surfactant and n-butanol as cosurfactant, the microemulsion systems of different systems were prepared, and the interfacial tension and particle size distribution curves were measured. Viscosity and stability parameters. The microemulsion prepared by dodecyl betaine was selected for physical simulation experiment. The starting pressure gradient, relative permeability curve and residual oil of lithographic glass model were measured with low permeability core in Daqing Oilfield. The mechanism of increasing oil recovery by microemulsion was analyzed from different angles by microemulsion flooding experiment and core microdissection experiment. The surfactant in the microemulsion can be adsorbed on the rock surface, which greatly reduces the solid-liquid interfacial tension and the flow resistance of the boundary layer fluid. When the displacement pressure difference is small, the fluid in the fine pore can overcome the adhesion force and participate in the flow. At the same time ionic surfactants can dissociate a certain amount of charges which can adsorb on the surface of the boundary layer fluid and compress and diffuse the double electric layer thus reducing the thickness of the boundary layer and increasing the actual overcurrent area of the pore. Therefore, the microemulsion system can greatly reduce the starting pressure gradient of the core and reduce the resistance in the seepage process. The decrease of oil-water interfacial tension makes it easier to deform the oil droplets, weakens the additional resistance produced by the Jamin effect, increases the relative permeability of the oil phase, and decreases the residual oil saturation. The displacement effect of microemulsion on oil droplet residual oil and membrane residual oil is the best, while that on blind terminal residual oil is the worst. Throat radius and pore throat ratio are the most important factors affecting the oil displacement effect of microemulsion. The microemulsion can reduce the interfacial tension and the starting pressure gradient, improve the oil-water mobility ratio, so the oil recovery can be greatly improved.
【学位授予单位】：东北石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE357.46

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