The Research Of Preparation And Modification Of Nano Silicon Dioxide Used For Oil Displacement

Nanomaterials liquid has a large surface area and high surface energy.Oil recovery with nanomaterials liquid is a kind of new oil production technology.It can greatly reduce the oil-water interfacial tension and result in stripping form small droplets of oil.Additionaly,the nanomaterials liquid can be spreaded to crude oil that was not touched with traditional method to improve the recovery efficiency because the small hole in statum can temporarily be blocked with the nano-particle in liquid.Among them,the nano SiO₂ oil displacement agent shows good shear thickening thixotropy,at the same time shows excellent performance in reduceing pressure augmented injection and blocking the hole so that be widely followed.But because of the bad compatibility with crude oil,the small degree to reduce the oil-water interfacial tension,and the influence of the wettability of the rock when adsorpted to surface,therefore,surface modification to change its performance is rather necessary.In this thesis,nano SiO₂ was synthesized and modified with different silane coupling agents to change the wettability and reduce the interfacial tension of SiO₂ for using in nanomaterials liquid to regulate the wettability,reduce oil-water interfacial tension,improve the efficiency of washing oil.The results were as follows.?1?A new type of non-ionic and anionic type alkoxy silane coupling agent was synthesized through a silicon hydrogen addition reaction and the conversion rate can reach 91.3%,which can be used to improve the activity of of nano SiO₂.It reduced surface tension to 33.8mN·m-1 when the corresponding CMC was 10.96×10-3 g·m L-1.The surface tension at the corresponding CMC increased with increasing the molecular weight of the product,while the CMC reduced.?2?The modified nano SiO₂ can successfully regulate the wettability.The longer of the hydrophobic chain,the more hydrophobic.The more weak hydrophilic groups,the more hydrophobic.The wettability of the modified nano SiO₂ products were mainly affected by the concentration of modified agent,and the wettability was about proportional the concentration of modified agent to some extent.?3?The modified nano SiO₂ showed a great interfacial activity.The nano SiO₂ modified by the products of AEPH300 and Si?CH3CH2O?3H through silicon hydrogen addition reaction showed the strongest ability to reduce the oil-water interfacial tension,which can reach as low as 9.0 N·m-1,while nano SiO₂ without modification can only reach 17.4 N·m-1.?4?In the oil-washing experiments,nano SiO₂ modified by the products of AEPH300 and Si?CH3CH2O?3H through silicon hydrogen addition reaction had the best performance.The nano SiO₂ modified by polyether series showed better results than that modified by long chain alkyl silane coupling agent.In a word,the modified nano SiO₂ solution is a kind of oil displacement agent with high efficiency.And the wettability can be controlled by modified agent types,number,chain length,concentration etc..The nanomaterials liqud can reduce the oil/water interfacial tension to as low as 9.0 N·m-1,and have a good performance in oil-washing experiment.