Study On Synthesis And Properties Of Nano-silicon Dioxide Composite Pour-point Depressants

Because the wax component of high waxy crude oil has a great influence on the low temperature fluidity of oil,it will lead to the increase of oil pour point;viscosity,even blockage of pipelines in serious time,result in serious production and economic problems,so it is very important to choose an effective treatment method for this kind of phenomenon.The usual way to deal with the problem is to add a pour point depressant,However,there are many limitations of conventional depressant.In this paper,a new nanometer compound depressant is prepared by combining EVA with nanometer materials to achieve better effect on low temperature fluidity.First of all,nano-silica's surface treatment was using silane coupling agent and stearic acid for its organic modification,and composite with EVA to prepare of nano-composite depressant.By comparing the effect of modified and unmodified nano silicon dioxide composite with EVA after applied to the model oil,the effect of organic modified nano-composite depressant was improved,and the optimum ratio of organic modified nano-silica and EVA was determined,which was the standard ratio for subsequent preparation of compound depressant.The effects of three kinds of pour depressant(pure EVA depressant,S/E containing nano-compound depressant and OS/E containing nano-compound depressant)on the low temperature fluidity and the shape structure of wax crystal added in three different wax content(20%;25%;30%)model oil were studied.And also the effect of OS/E containing nano-compound depressant with different vinyl acetate(VA=28%;32%;40%)content on the low temperature fluidity and crystal morphology of model oil with wax content of 25%.The results showed that the nano-compound depressant containing OS/E had the best efficiency,and the reason of its excellent effect was further analyzed,and the mechanism of pour point decline was investigated according to the polarizing microscopic image.In addition to the influence of wax composition on the system in crude oil,the effect of colloid composition in crude oil on the effect of nano-compound depressant is also studied,the dilution method is used to prepare the model oil with different colloid content,and it is found that the content of colloid component has no great influence on the initial pour point.However,the existence of colloid will make the nano-composite depressant surface adsorption selectivity disrupted,and lead to the competition with the depressant of wax crystallization,the resulting wax crystal size is not uniform and compact,which makes the drop of system fluidity.