纳米复合材料稠油降粘剂的研制与性能评价

发布时间：2018-09-16 19:06

【摘要】：稠油是世界油气资源的重要组成部分,现代社会对能源的需求和消耗越来越大,石油储量特别是轻质原油储量正迅速减少,而稠油资源相对丰富,未来社会对石油的需求将由稠油来满足。稠油的组成比较复杂,含有大量的蜡质、胶质和沥青质,导致其具有凝点高、粘度大、流动性差的特点,开采和运输困难大、成本高。因此降低稠油粘度,增强稠油流动性成为近年来油田化学研究的热点和难点问题。化学降粘剂降粘法以其加量少、耗能低、操作简单、无后处理程序等优点被认为是解决稠油开采和输送问题最有前途的方法。纳米材料降粘剂是一种新型化学降粘剂,它能依靠其自身特殊的纳米效应,改变稠油中蜡质的结晶行为和胶质、沥青质的聚集方式,从而提高稠油的低温流动性,对于高蜡稠油效果更为突出。采用硅烷偶联剂KH550和十八酸在溶剂乙醇中对纳米Si02进行两步表面改性,制备了纳米KH550-C18/SiO2复合材料降粘剂。以接枝率为评价指标,通过实验确定最佳改性剂用量为：KH550和十八酸用量分别为Si02质量的16%和20%。为进一步提高纳米复合材料中有机成分的含量,并且引入强极性基团,以硅烷偶联剂KH570、甲基丙烯酸十八酯和丙烯酰胺为接枝单体在纳米Si02表面引发接枝共聚反应,制备了纳米PSMA-AM/SiO2复合材料降粘剂。通过红外光谱(FT-IR)、热重分析(TG)、透射电镜(TEM)、扫描电镜(SEM)以及接触角测试等手段对两种复合材料的结构和性质进行分析表征。结果表明,经两种方法改性后,纳米Si02表面都由亲水性变为疏水性,聚集程度降低,在有机溶剂中表现出良好的分散稳定性,其中,纳米PSMA-AM/SiO2复合材料的接枝率更高,与水的接触角更大。以大庆高蜡稠油为研究对象,测试了油溶性降粘剂EVA及本研究合成的两种纳米复合材料降粘剂的降粘效果,改变温度和加入量,探究其对降粘率的影响。随加入量增大,降粘率先升高后基本保持不变,略有下降趋势。纳米KH550-C18/SiO2在最佳加量600ppm时,能使稠油的析蜡点降低3.6℃,40℃的表观降粘率为66.91%,净降粘率为40.32%,纳米PSMA-AM/SiO2在最佳加量400ppm时能使析蜡点降低5.5℃,在40℃表观降粘率为72.1%,净降粘率为48.86%。两种纳米复合材料的降粘效果都优于EVA,纳米PSMA-AM/SiO2由于有机成分的含量更高,极性更强,所以性能更为优异。三种降粘剂的降粘率都随温度升高而下降,EVA下降速度最快,在60℃时仅为19%,而纳米复合材料降粘剂在稍高温区50℃-60℃时,仍能保持净降粘率在30%以上。对纳米复合材料降粘剂的降粘机理进行了探究和分析：纳米颗粒利用特殊的表面效应能够作为成核点吸附蜡质在表面结晶、析出,改变蜡质的结晶行为,破坏蜡晶原有的三维网状结构；同时纳米颗粒表面所引入的强极性基团通过氢键作用吸附胶质、沥青质在其表面形成溶剂化层,溶剂化层的存在既能阻止蜡晶之间连接形成网状结构,又能拆散原稠油体系中胶质和沥青质的平面重叠堆砌结构,从而使稠油粘度大幅降低。
[Abstract]:Heavy oil is an important part of the world's oil and gas resources. The demand and consumption of energy in modern society is increasing. The reserves of oil, especially light crude oil, are decreasing rapidly. Heavy oil resources are relatively rich. The demand for oil in the future society will be met by heavy oil. The composition of heavy oil is relatively complex and contains a lot of wax, gum and leach. It is difficult to recover and transport heavy oil because of its high solidification point, high viscosity and poor fluidity. Therefore, reducing viscosity and enhancing fluidity of heavy oil have become hot and difficult problems in recent years. Nano-material viscosity reducer is a new kind of chemical viscosity reducer. It can change the crystallization behavior of wax in heavy oil and the aggregation mode of gum and asphaltene depending on its own special nano-effect, so as to improve the low-temperature fluidity of heavy oil, especially for high-wax heavy oil. Nano-KH550-C18/SiO2 composite viscosity reducer was prepared by two-step surface modification of nano-Si02 with silane coupling agent KH550 and octadecanoic acid in solvent ethanol. The optimum dosage of the modifier was determined by experiment as 16% and 20% of the mass of Si02 respectively with the grafting rate as the evaluation index. Nano-PSMA-AM/SiO2 viscosity reducer was prepared by graft copolymerization of silane coupling agent KH570, octadecyl methacrylate and acrylamide onto the surface of nano-Si02, and the content of organic components in nano-SiO2 composite was introduced. The viscosity reducer was prepared by FT-IR, TG and TEM. The results showed that the surface of nano-Si02 changed from hydrophilic to hydrophobic, and the degree of aggregation decreased. The nano-PSMA-AM/SiO2 composites exhibited good dispersion stability in organic solvents. The viscosity reduction effect of oil-soluble viscosity reducer EVA and two kinds of nano-composite viscosity reducers synthesized in this study were tested. The effect of temperature and addition on viscosity reduction rate was studied. With the increase of addition, viscosity reduction rate increased first and then remained unchanged. At the optimum dosage of 600 ppm, nano-KH550-C18/SiO2 can reduce the wax precipitation point of heavy oil by 3.6 C, the apparent viscosity reduction rate at 40 C is 66.91%, the net viscosity reduction rate is 40.32%, the nano-PSMA-AM/SiO2 can reduce the wax precipitation point by 5.5 C at the optimum dosage of 400 ppm, the apparent viscosity reduction rate at 40 C is 72.1%, and the net viscosity reduction rate is 48.86%. The viscosity reduction rate of the three kinds of viscosity reducers decreased with the increase of temperature, and the EVA decreased fastest, only 19% at 60 C, while the nanocomposite viscosity reducer still maintained a net drop at a slightly high temperature range of 50 60 C. The viscosity reduction mechanism of nanocomposites was studied and analyzed. Nanoparticles could be used as nucleation point to absorb wax on the surface and crystallize, precipitate, change the crystallization behavior of wax, destroy the original three-dimensional network structure of wax. At the same time, the introduction of strong poles on the surface of nanoparticles. The group adsorbs the gum through hydrogen bonding, and the asphaltene forms a solvation layer on its surface. The existence of the solvation layer not only prevents the connection between wax crystals to form a network structure, but also dismantles the planar overlapping structure of gum and asphaltene in the original heavy oil system, thus greatly reducing the viscosity of heavy oil.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB332

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