2-D智能纳米黑卡稳定乳状液的机理

Mechanisms of Stabilizing Pickering Emulsions by Two-dimensional Smart Black Nano-card

为揭示二维纳米片状材料(黑卡)对乳状液稳定性的影响,以扶余油田长春岭和三队区块原油为例,在水油体积比为7∶3的条件下,研究质量分数为0.005%的2-D智能纳米黑卡流体对原油乳状液稳定性的影响。通过稳定性分析仪和界面流变仪表征乳状液稳定性大小和界面膜强度,通过观察乳状液的微观形状和粒径分布分析黑卡增强乳状液稳定性的机理。研究结果表明,黑卡尺寸约为70×100(nm),厚度为0.65数1.2 nm。在原油和0.01%稳定剂十六烷基三甲基溴化铵(CTAB)组成的乳状液中加入黑卡后形成Pickering乳状液,乳状液的析水速度变慢,乳状液的稳定析水率从75.71%数78.57%降至65.71%数72.86%;乳状液稳定性提高,稳定性指数(TSI)值由4.73数5.64降至2.71数3.84;乳状液膜的强度增强,体系流变学特征由黏性转变为明显的弹性。黑卡作用的Pickering乳状液的背散射光曲线可分为乳状液破乳区、过渡区和乳状液聚并区3个区域。黑卡能改变稳定剂亲水-亲油平衡,将W/O型乳状液转变为O/W型乳状液,形成液滴尺寸为0.1数5μm大小的乳状液,大幅降低原油黏度。黑卡同时具有亲水-亲油两亲性质,可通过自吸附定向排布于液膜上,增加液膜强度,提高乳状液稳定性。图21表3参22。

In order to reveal the influence of two-dimensional nanosheet material(2-D smart black nano-card)on the stability of crude oil emulsion,taking the crude oil of Changchunling and Third Block of Fuyu oilfield as an example,the effect of 2-D smart black nano-card fluid with a mass fraction of 0.005%on the stability of crude oil emulsion was studied under the condition of 7∶3 water-oil volume ratio.The stability and interfacial film strength of crude oil emulsion were analyzed using stability analyzer and interfacial rheological instrument.The mechanism of smart black nano-card on enhancing the stability of emulsion was analyzed by observing the microscopic shape and particle size distribution of emulsion.The results showed that the size of smart black nano-card was about 70 nm×100 nm and the thickness was 0.65—1.2 nm.The Pickering emulsion was formed by adding smart black nano-card to the emulsion composed of crude oil and 0.01%stabilizer cetyl trimethylammonium bromide(CTAB).The ultimate dewatering rates of the emulsions slowed down,which decreased from 75.71%—78.57%to 65.71%—72.86%.The stability of emulsion increased and the turbiscan stability index(TSI)value decreased from 4.73—5.64 to 2.71—3.84.The strength of the emulsion film increased and the rheological characteristic of the system changed from viscosity to apparent elasticity.The backscattering spectra of the Pickering emulsions with smart black nano-card could be divided into three regions,such as emulsion demulsification zone,transition zone and emulsion coalescence zone.Smart black nano-card could change the hydrophilic-lipophilic balance of stabilizer,transform W/O emulsion into O/W emulsion and form emulsion with droplet size of 0.1—5μm,resulting in greatly viscosity reduction of crude oil.Smart black nano-card had hydrophilic-lipophilic amphiphilic property,which could arrange on the liquid film through self-adsorption,increase the strength of liquid film and improve the stability of emulsion.