树枝状介孔纳米材料形貌调控机制及驱油性能

Morphology regulation mechanism and oil displacement performance of dendritic mesoporous nanomaterials

首先,以硅酸四乙酯(TEOS)和尿素为原料、十六烷基三甲基溴化铵(CTAB)为模板剂,通过双连续相微乳液法制备了树枝状介孔纳米材料(DMSNs),然后将丙烯酰胺与2-丙烯酰胺基-2-甲基丙磺酸二元聚合物[P(AM-AMPS)]以质量分数0.05%(以DMSNs分散体系质量计)加入DMSNs分散体系形成DMSNs流体。采用FTIR、XRD、SEM、TEM、N_(2)吸附-脱附对DMSNs进行了表征,考察了反应时间、TEOS添加量(以对二甲苯体积计,下同)、共溶剂、搅拌速率和反应温度对DMSNs性能的影响,探究了DMSNs米流体的润湿性及驱油性能。在反应时间6 h、TEOS添加量25%、以乙二醇为共溶剂、搅拌速率1000 r/min和反应温度85℃的最佳条件下,制备的DMSNs平均粒径为91 nm,比表面积为1094.75 m^(2)/g,孔隙体积为1.862 cm^(3)/g,平均孔径为6.1 nm;DMSNs表面具有特殊的褶皱形态,呈现“片状/层状”的花状介孔结构。DMSNs含量(以去离子水质量为基准,下同)0.10%的DMSNs流体能使岩石的润湿性从油湿性转变为水湿性,油相(正十六烷)接触角从0°增加到132°,可有效改变岩石润湿性,显著提高三次采收率(39.6%);DMSNs的制备过程为竞争性成核和生长机制,分为初始成核、纵向生长、二次成核+横向生长3个阶段。

Dendritic mesoporous nanomaterials (DMSNs) were prepared by bicontinuous microemulsion method using tetraethyl orthosilicate (TEOS) and urea as raw materials,hexadecyl trimethyl ammonium bromide (CTAB) as template.Then,the acrylamide and 2-acrylamide-2-methylpropanesulfonic acid dibasic polymer P(AM-AMPS) were added to the DMSNs dispersion system at 0.05%(mass fraction,by mass of the DMSNs dispersion system) to form the DMSNs fluid.And the DMSN characterized by FTIR,XRD,SEM,TEM,N_(2) adsorption-desorption.The effects of reaction time,TEOS addition amount (based on paraxylene volume,the same below),cosolvent,stirring rate and reaction temperature on the properties of DMSNs were analyzed,while the wettability and oil displacement performance of DMSNS nanofluids were further evaluated.Under the optimal conditions of reaction time 6 h,TEOS addition amount 25%,ethylene glycol as cosolvent,stirring rate 1000 r/min and reaction temperature 85℃,the prepared DMSNs showed an average particle size of 91 nm,specific surface area of 1094.75 m^(2)/g,pore volume of 1.862 cm^(3)/g,and average pore size of 6.1 nm.The surface of DMSNs exhibited a special wrinkle morphology,presenting a"flake/layered"flower-like mesoporous structure.The DMSNs nanofluid with 0.10% DMSNs content(based on the mass of deionized water,the same below) could change the rock wettability from oil-wet to water-wet,with the contact angle increased from 0° to 132°,and the change in rock wettability significantly improved the tertiary oil recovery (39.6%).The competitive nucleation and growth mechanism in the formation of DMSNs consisted of three processes,namely initial nucleation,longitudinal growth,and secondary nucleation+lateral growth.