高密度接枝梳状聚合物的聚巯基硅微纳米球复合防蜡剂对蜡油蜡沉积特性的调控机理研究

Adding polymeric wax inhibitors is an effective method to inhibit the wax deposit of crude oil pipelines, but many problems are also encountered such as the unsatisfactory wax inhibiting performance, the insufficient thermal/shearing resistance, the unclear action mechanism, etc. Developing the grafted composite wax inhibitor and increasing the grafting amount of the polymeric wax inhibitor on the surface of micro-/nano-particles is a promising research direction. Using the unique morphology and structure of polysulfhydryl-silicon micro-/nano-spheres and the advantage of thiol-ene click reaction, this project will graft the comb polymers onto the polysulfhydryl-silicon micro-/nano-spheres to prepare the composite wax inhibitor, aiming to significantly change the wax crystal morphology, structure and state of aggregation, thus regulating the wax deposit characteristics, and setting up the correlation of composite wax inhibitor’s structure and performance and revealing the regulation mechanism of wax deposit characteristics motivated by the composite wax inhibitor. Firstly, the polysulfhydryl-silicon micro-/nano-spheres will be prepared and the high-density comb-like polymers will be grafted by using thiol-ene click reaction to prepare the composite wax inhibitor. Secondly, the regulation rules of the composite wax inhibitor structure, wax oil composition and pipeline transportation process conditions on the deposition rate, the composition, macro and micro structure of deposit will be studied in detail. The correlation between the structure and wax inhibiting performance of the composite wax inhibitor will be established by using the fuzzy clustering analysis method. Finally, with the help of computer multi-scale simulation and theoretical analysis, the regulation mechanism of composite wax inhibitor on wax deposition characteristics will be revealed. This project will promote the preparing and theoretical development of novel and highly-efficient paraffin inhibitor, which is of great significance to the safe and efficient transportation of waxy crude oil.

添加聚合物型防蜡剂是有效的原油管道防蜡方法，但其存在效果不理想、热力/机械稳定性不足、作用机理不明确等问题。开发接枝型复合防蜡剂并提高聚合物在微纳米颗粒表面的接枝量是极具潜力的发展方向。本项目利用巯基-烯点击反应的优势和聚巯基硅微纳米球独特的形貌与结构，在聚巯基硅微纳米球表面高密度地接枝梳状聚合物以制备复合防蜡剂，显著改变蜡油析出蜡晶形貌、结构与聚集状态，从而调控蜡油蜡沉积特性。首先，制备聚巯基硅微纳米球并采用巯基-烯点击反应接枝高密度梳状聚合物，制得复合防蜡剂；其次，研究复合防蜡剂结构、蜡油组成、管输工艺条件等因素对沉积速率、沉积物组成、宏观与微观结构等蜡沉积特性的调控规律，利用模糊聚类分析建立复合防蜡剂微观结构与性能的相关性；最后，借助计算机多尺度模拟与理论分析，揭示复合防蜡剂对蜡油蜡沉积特性的调控机理。本项目将促进新型高效防蜡剂的开发与理论发展，对含蜡原油安全高效的输送具有重要意义。

通过水解-缩聚反应（即溶胶-凝胶法）制备聚巯基硅（PMPSQ）纳米球并对其进行表征；然后通过巯基-烯点击反应在PMPSQ表面接枝丙烯酸十八酯（OA）单体，得到高接枝密度的接枝型纳米降凝剂（PMPSQ-OA），并探究其对多种蜡油体系的流变改善效果及改善机理。为制备出形貌完整的纳米球，水解反应时间应控制在4 h左右，水相pH值应小于4；而缩聚反应时间不低于4 h，水相pH应大于11，且MPTMS质量分数应不高于5%。随着MPTMS质量分数的降低和搅拌速率的增大，纳米球的粒径不断减小，例如搅拌转速由100 r·min-1增大到900 r·min-1时，纳米球平均粒径由923 nm减小到601.7 nm。随着反应温度的升高，所制备纳米球的平均粒径先减小后增大。利用巯基-烯点击反应成功制备了接枝型纳米降凝剂PMPSQ-OA。光引发剂BDK浓度显著影响PMPSQ-OA的表面接枝率和性能：当OA和巯基摩尔比为1：1时，随着BDK浓度的提高，纳米球的表面接枝率、结晶能力和降凝降粘性能均不断提高并在BDK浓度为4%时达到最大接枝率（78.53%）；继续提高BDK浓度到6%时，表面接枝率反而明显下降（59.85%），PMPSQ-OA的结晶能力和降凝降粘性能也显著变差。控制引发剂用量为4%，改变点击反应中烷基链OA的浓度，随着OA浓度的增大，纳米球表面的接枝率逐渐增大，PMPSQ-OA-1~4降凝剂的结晶性能和在油相中的分散能力逐渐增强，OA与巯基摩尔比为1：1时（PMPSQ-OA-4），500ppm接枝型降凝剂可以使长庆原油凝点降低14 °C，平均降粘率为87.27%，流变性改善效果最好。继续增大OA单体浓度到OA与巯基摩尔比为5：1（PMPSQ-OA-5），纳米球表面的接枝率没有显著的增长，原油的流变性没有进一步改善。随着PMPSQ-OA-4接枝型降凝剂加剂浓度的升高，长庆原油的流变性改善效果变好。将PMPSQ-OA-4降凝剂添加到青海原油和人工蜡油中，同样表现出了良好的降凝降粘作用，例如添加500ppm PMPSQ-OA-4于人工蜡油中，凝点由25 °C降低到了11 °C。观察蜡晶显微照片发现，PMPSQ-OA降凝剂能够改变蜡晶的结晶特性，使蜡晶从细长的针状结构变成致密的，短而粗的棒状结构，同时促进了蜡晶的团聚，减少了晶液面积，从而改善了蜡油的流变性能。