【作者】 姚博； 李传宪； 杨飞； 张莹； 肖作曲；

【Author】 YAO Bo;LI Chuanxian;YANG Fei;ZHANG Yin;XIAO Zuoqu;College of Pipeline and Civil Engineering,China University of Petroleum;

【机构】 中国石油大学(华东)储运与建筑工程学院；

【摘要】 含蜡原油在世界原油产量中占了很大的比例,高含蜡原油的开采、储运等相关问题日趋成为石油行业的研究热点。含蜡原油在温度降低至析蜡点后,蜡晶将以针状或片状的形式进一步析出,蜡晶与蜡晶之间相互搭接,形成网络卡片房状结构,将液相包覆其中,原油体系开始由溶胶向凝胶转变,导致含蜡原油凝点高、低温粘度高、结构屈服值大、低温流变性差^[1]。在集输或长输现场应用中,添加降凝剂对含蜡原油进行化学改性输送是一种行之有效的方法。但传统聚合物型降凝剂仍存在许多应用问题,如对某些原油降凝降粘效果不理想、时效性差、抗剪切抗重复加热能力差等,故亟需展开对新型降凝剂的开发工作,深入研究降凝剂的作用规律与机理^[2-3]。本文首先使用了阳离子表面活性剂十八烷基三甲基氯化铵（OTAC）,通过离子插层交换对天然无机纳米粘土进行了有机化改性。以甲苯为溶剂,在不同浓度、不同温度、不同搅拌强度下,通过溶液共混法制备了聚丙烯酸十八酯（POA）/改性粘土纳米复合降凝剂,并利用了XRD、IR、TEM、SEM、PEM等表征手段对纳米复合降凝剂的结构进行了表征,结果显示纳米复合降凝剂是插层剥离型复合材料结构,并且能在油相体系中均匀分散。选用典型的含蜡原油长庆原油作为实验油样,DSC、CS流变仪、偏光显微观察结果显示,相较于相同加剂条件下的纯POA降凝剂,复合降凝剂会提高原油的析蜡点,却能进一步降低原油胶凝点、粘度与结构屈服值,油样低温微观蜡晶结构更为完整、紧凑,相互絮凝能力更弱。更多还原

【Abstract】 In this article,the nanoclay is first hydrophobically intercalated by cationic surface active agentoctadecyl trimethyl ammonium chloride(OTAC) to enhance its lipophilicity and strengthen the interaction between nanoclay and POA pour point depressants(PPDs).A novel poly octadecyl acrylate(POA)/ modified clay nanocomposite PPD is developed through melt blending process and analyzed through XRD,FT-IR and microscopic observation.Then its activity performance is demonstratedusing Changqing waxy crude oil.Results show that,compared with the same concentration of pure POA PPD,POA/clay nanocomposite PPD leads a better performance on the rheology improvement of crude oil,upon which a further reduction in gelation point,nonNewton viscosity and yield stressis observed.Differential scanning calorimetry(DSC) data confirms that POA PPD can enhance the supersaturation degree of wax molecules in oil phase,resulting in the decrease of WAT(wax appearance temperature),while composite PPD brings up the WAT again.Microscopic images of the treated crude oil samples are recorded by polarization electron microscope,from which it can be seen that modified nanoclay just acts as the heterogeneous nucleation sites when POA and wax crystals precipitate,tending to modify the wax crystal morphology to a more compact,spherical-like and no small wax crystals existing microstructure,thus modulating the macroscopic rheology for Changqing waxy crude oil.In addition,the improving mechanism of the nanocomposite PPD on crude oil rheology is discussed in detail.更多还原