Abstract

Nowadays, most of the studies on oil displacement mechanisms are macroscopic, indirect, and empirical, lacking research with respect to the interactions between heavy oil and rock mineral at a molecular level. In this paper, in order to deeply explore the microscopic oil displacement mechanism, molecular interactions at the interface between heavy oil and rock mineral were characterized and analyzed with an in-situ and direct mechanics method, via preparing Atomic Force Microscope (AFM) -N-(1-hexylheptyl)-N’-(12-carboxylicdodecyl)perylene-3,4,9,10-tetracarboxylbisimide (C5Pe) probes and measuring adhesion with different substrates. Effects of substrates (calcium carbonate, mica and silicon dioxide), cations (Ca²⁺, Na⁺), salinities (100, 10 mmol/L) and pH (4, 7 and 10) on molecular interactions were investigated. C5Pe, as a model molecule of asphaltene, had the molecular interaction strength with minerals as the following sequence: calcium carbonate > mica > silicon dioxide. Salt effect study results showed that the molecular interactions in CaCl₂ solution were stronger than that in NaCl solution at the same salt concentration, which increased with the increase of salinity. Besides, increasing the pH value, the molecular interactions at the interface were weakened, resulting in an easier oil flooding. The conclusions as above manifested that oil flooding was easier in lower salinity with the order of rock minerals: silicon dioxide > mica > calcium carbonate.

摘要

如今，大多数关于驱油机理的研究都是宏观的，间接的和经验的，而在分子水平上缺乏关于重油与岩石矿物之间相互作用的研究。为了深入探讨微观驱油机理，通过制备原子力显微镜（AFM）-N，采用原位直接力学方法表征和分析了稠油与岩石矿物界面的分子相互作用。 -（1-己基庚基）-N'-（12-羧基十二烷基）per-3,4,9,10-四羧基双酰亚胺（C5Pe）探针，并测量与不同基材的粘合力。底物（碳酸钙，云母和二氧化硅），阳离子（Ca 2 ⁺，Na ⁺），盐度（100、10 mmol / L）和pH（4、7和10）对分子相互作用的影响。C5Pe作为沥青质的模型分子，具有与矿物的分子相互作用强度，顺序为：碳酸钙>云母>二氧化硅。盐效应研究结果表明，在相同盐浓度下，CaCl ₂溶液中的分子相互作用强于NaCl溶液中，并且随着盐度的增加而增强。此外，增加pH值，界面处的分子相互作用减弱，导致油驱更容易。以上结论表明，在较低盐度的情况下，按照岩石矿物顺序依次为：二氧化硅>云母>碳酸钙。