【作者】 蒋平；

【导师】 张琪； 张贵才；

【作者基本信息】 中国石油大学 ， 油气田开发工程， 2009， 博士

【摘要】 化学驱技术是进一步提高稠油油藏采收率的有效手段,为了研究稠油油藏提高采收率的机理,构建了具有不同界面张力和乳化能力的驱油体系,首先确定了具有不同结构的含氧丙烯链节的阴离子表面活性剂以及烷基羧基甜菜碱与桩西稠油的界面张力特点,研究表明含有氧丙烯链节的阴离子表面活性剂界面张力随盐含量增加先降低后升高,增加PO数和烷烃碳数有利于降低界面张力。十四烷基羧基甜菜碱和十六烷基甜菜碱的界面张力随着活性剂浓度的升高而升高,增加矿化度有利于降低油水界面张力;十八烷基甜菜碱的界面张力随着活性剂浓度和矿化度的增加先降低后升高。表面活性剂与Na2CO3复配体系中,当Na2CO3浓度大于0.35%时协同效应显著,表面活性剂在较低的使用浓度下,就可以达到超低界面张力。其次采用最小乳化转速法研究了不同表面活性剂的乳化能力,研究表明9AS-n-0和13AS-n-0的乳化性能随矿化度的变化呈现“抛物线”的变化趋势,但是体系的乳化性能和动态平衡界面张力及动态初始界面张力都没有明显对应关系,其影响因素比较复杂;烷基甜菜碱对桩西原油的乳化能力优于9AS和13AS系列的表面活性剂,增加甜菜碱使用浓度和矿化度有利于增强体系的乳化能力。建立了油膜收缩速率的测定方法,评价了在表面活性剂溶液和碳酸钠溶液中的油膜收缩速率,研究表明活性剂通过降低水-固界面张力和油-水界面张力加速了油膜的收缩;碱与原油反应产生的表面活性物质可以吸附在油-固界面上降低油-固界面张力,增强固体表面的亲油性,降低油膜的收缩速率。在前面工作的基础上构建了界面张力、乳化能力不同的17种驱油体系,对这些体系进行了36次物理模拟评价,发现乳化能力是取得好驱油效果的必要条件而非充分条件、稠油化学驱的采收率与驱油体系的油水界面张力没有对应关系。实验表明低界面张力、高乳化速率和油膜收缩速率有利于提高分散残余油的采收率;低油膜收缩速率对提高驱替介质在高含油饱和度区域的波及体积至关重要。碱通过维持油/水/固三相接触点亲油性和降低油-水界面张力,减弱了驱替介质沿油与岩石之间的渗入,增强了驱替介质从原油中心的突进和分散,提高了驱替压力和波及体积。该发现对稠油油藏化学驱的设计具有指导意义。更多还原

【Abstract】 The chemical flooding is an effect way to enhance oil recovery for heavy oil reservoir. The systems with different IFT and emulsifying power were setup to research the mechanism for enhancing heavy oil recovery. The IFT for anionic surfactant with propylene oxide and betaine were studied. The IFT for anionic surfactant with propylene oxide increase before decrease with the increase of the salinity, and decrease with the increase of the number of PO and carbon chain. The IFT for tetradecyl betaine and hexadecyl betaine increases with the increase of surfactant concentration. The increase for salinity is favor for decrease the IFT. The IFT of octadecyl betaine increase before decrease with the increase of the surfactant concentration and salinity. In surfactant and Na2CO3 system, it could reach the ultra-low IFT with low surfactant concentration if the Na2CO3 is more than 0.35%. The emulsifying power for surfactant is evaluated by the minimum emulsify rotate speed. The emulsifying power of 9AS-n-0 and 13AS-n-0 change with salinity as paracurve, but it has no relation with the IFT. The emulsifying power of betaine is better than 9AS and 13AS and it is enhanced by the increase of the surfactant concentration and salinity. The method to evaluate the oil film shrink velocity is built. The oil film shrink velocity in surfactant and Na2CO3 solution were researched. It shows that the surfactant could decrease the W/S and O/W IFT which is good for oil film shrink. The in-situ surfactant that comes from the reaction of Na2CO3 and oil acid could adsorb on the oil and solid surface to reduce the oil and solid surface interfacial tension which is bad for oil film shrink. The 17 kinds of systems with different ITF and emulsification ability were chosen. Thirty-six experiments were done. It shows that the displacement system with good emulsification ability is the necessary condition to get higher recovery. The recovery for heavy oil reservoir has no relation with IFT. It indicates that the system with low IFT and high emulsification ability and high oil film shrink velocity is good for enhancing separated oil recovery, and the system with low oil film shrink velocity could enhance recovery for the area with higher oil saturation. The sodium carbonate could keep the solid oil-wet and reduce the O-W IFT to prevent the water from penetrating between the oil and solid. It makes the displacement agent flow through the oil, and enhances the displacement pressure and sweep efficiency. The results are helpful to the chemical flooding for the heavy oil reservoir.更多还原