沥青质对模拟三元复合驱采出水乳液稳定性的影响

发布时间：2019-04-20 19:53

【摘要】：随着原油的不断开采,原油资源越来越少。为了提高原油采收率,越来越多的油田开始采用三元复合驱(碱、表面活性剂和聚合物)采油技术。另外,我国稠油和超稠油资源储量丰富,这些油中含有大量的沥青质等天然活性成分,与驱替液中的驱油剂相互作用,尤其是沥青质与驱油剂之间的相互作用,在油滴表面形成的界面膜,增加了采出水油水分离的难度。为了更好的对油田采出水进行工业处理,以达到回注或排放的标准,减轻对环境造成的污染,需要我们对三元复合驱采出水乳液稳定性的机理进行深入研究。因此,研究沥青质和驱油剂在油水界面上的相互作用机理对于油田采出水的处理具有重要的意义。本研究先是排除原油中复杂的天然活性成分,用轻质油作为模拟油,单独讨论外加驱油剂对三元复合驱采出水乳液稳定性作用的机理。在这个基础上,分别研究了三种驱油剂与沥青质在油水界面的相互作用机理以及对三元复合驱模拟采出水乳液稳定性的影响。采用超低界面张力仪、Zeta电位分析仪和界面流变仪对油水界面张力、动态界面张力、油滴表面Zeta电位和界面流变进行测定等表征手段,研究结果如下。(1)研究所用轻质油不含有沥青质、环烷酸等原油中的酸性成分,所以,碱对模拟采出水乳液稳定性影响较小。石油磺酸盐(WPS)作为表面活性剂能够很好的降低油水间界面张力,使模拟采出水的稳定性增强。部分水解聚丙烯酰胺(HPAM)作为聚合物增强了体相的黏度,对界面张力影响较小,但是增强了体相的黏度,通过空间位阻作用降低了油水分离的速率,对模拟采出水稳定性最终影响不大。矿化度升高使表面活性剂降低界面张力的能力和效率增强,含油量升高趋势明显,模拟采出水稳定性明显增强。(2)碱能够和沥青质分子中的一些酸性官能团反应,增强沥青质分子的亲水性,很大程度的降低油水界面张力,同时使沥青质分子具有更快的扩散速度,在动态界面张力中,快速衰减起主要作用。在油水界面上形成的空间网状结构更加密实,其界面黏弹性明显高于其它情形。表面活性剂和沥青质分子在油水界面上存在竞争性吸附。二者在界面吸附和解吸的可逆过程,以及在油水界面的重组都会延长吸附过程,慢速衰减起主要作用。HPAM具有较大的分子粒径和较高的分子量,影响了HPAM在界面上的活性和扩散,烷基链提供的空间位阻作用能够使溶解状态的沥青质难于聚集,在动态界面张力中,慢速衰减起主要作用。沥青质和ASP驱油剂在油水界面吸附,相互作用,使油滴表面吸附更多的负电荷,负电势增强。
[Abstract]:With the continuous exploitation of crude oil, crude oil resources are less and less. In order to improve oil recovery, more and more oil fields begin to use ASP flooding (alkali, surfactant and polymer) technology. In addition, China is rich in heavy and super heavy oil resources. These oils contain a large number of natural active components, such as asphaltene, and interact with displacement agents in displacement fluids, especially between asphaltenes and oil displacement agents. The interface film formed on the surface of oil droplets increases the difficulty of oil-water separation. In order to better treat the produced water from oil field in order to reach the standard of reinjection or discharge and reduce the pollution to the environment, it is necessary for us to study deeply the mechanism of emulsion stability of the produced water from ASP flooding. Therefore, the study of the interaction mechanism between asphaltene and oil displacement agent on the oil-water interface is of great significance for the treatment of oilfield produced water. In this study, the complex natural active components in crude oil were excluded, light oil was used as simulation oil, and the mechanism of the effect of oil displacement agent on the stability of ternary compound flooding effluent emulsion was discussed separately. On this basis, the interaction mechanism of three kinds of oil displacement agents with asphaltene at the oil-water interface and the influence on the stability of simulated effluent emulsion of ASP flooding were studied respectively. The interfacial tension of oil-water, dynamic interfacial tension, Zeta potential and interfacial rheology of oil droplets were measured by ultra-low interfacial tension meter, Zeta potential analyzer and interfacial rheometer. The results are as follows. (1) the light oil used in the study does not contain the acidic components in crude oil such as asphaltene and naphthenic acid, so alkali has little effect on the stability of simulated effluent emulsion. Petroleum sulfonate (WPS) as surfactant can reduce the interfacial tension between oil and water and enhance the stability of simulated produced water. Partially hydrolyzed polyacrylamide (HPAM) enhances the viscosity of bulk phase as a polymer and has little effect on interfacial tension, but enhances the viscosity of bulk phase, and reduces the oil-water separation rate by steric resistance. It has little effect on the stability of simulated produced water. The increase of salinity enhances the ability and efficiency of surfactant to reduce interfacial tension, and the increasing trend of oil content. (2) Alkali can react with some acidic functional groups in asphaltene molecules, and the stability of simulated produced water is obviously enhanced. (2) Alkali can react with some acidic functional groups in asphaltene molecules. By enhancing the hydrophilicity of asphaltene molecules, the interfacial tension between oil and water is greatly reduced, and the asphaltene molecules are diffused faster. In the dynamic interfacial tension, the rapid attenuation plays a major role. The spatial reticulated structure formed on the oil-water interface is more dense and the interfacial viscoelasticity is obviously higher than that in other cases. There is competitive adsorption of surfactant and asphaltene molecules on the oil-water interface. The reversible process of adsorption and desorption at the interface, as well as the recombination at the oil-water interface, can prolong the adsorption process, and slow decay plays a major role. HPAM has a larger molecular size and a higher molecular weight. The activity and diffusion of HPAM at the interface are affected. The steric hindrance provided by alkyl chain can make the asphaltene in dissolved state difficult to aggregate. In dynamic interfacial tension, slow decay plays a major role. Asphaltene and ASP oil displacement agent adsorption on the oil-water interface, interaction, so that the surface of oil droplets adsorption of more negative charges, negative potential enhanced.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X741

【相似文献】