Effect and mechanism of BEM/PMSQ hybrid pour point depressant on Qinghai waxy crude oil

doi:10.11949/j.issn.0438-1157.20170249

Abstract

Abstract:

Based on the outstanding organic compatibility and the micro spherical morphology of polymethylsilsesquioxane (PMSQ) microspheres, BEM/PMSQ hybrid pour point depressant was prepared by melt blending method. Then, the effect of BEM/PMSQ hybrid pour point depressant on the pour point, viscoelasticity, viscosity and yield value of Qinghai waxy crude oil was evaluated by rheological experiment and the morphology of wax crystals was observed by the polarizing microscope. The results showed that the pour point of the undoped crude oil was 27.0℃; compared with the same dosage of the neat BEM (100 μg·g^-1), BEM/PMSQ 2% hybrid pour point depressant has the best performance, which can further reduce the pour point of 6.0℃, the gelation point of 4.3℃, the apparent viscosity of 39.0% and G' of 62.0%. The dispersion state of PMSQ microspheres and BEM/PMSQ hybrid pour point depressant in the dodecane showed that BEM were adsorbed on the surface of PMSQ microspheres, and acted as the wax crystal nucleation templates in the crude oil, thus resulting in the formation of the compact wax crystal structure and coating with less liquid oil, so as to improve the rheology of crude oil.

Key words: pour point depressant, waxy crude oil, BEM, PMSQ, rheological property

摘要：

基于聚甲基硅倍半氧烷（PMSQ）微球良好的有机相容性与规则的微观球形形貌，将PMSQ微球与BEM降凝剂通过熔融共混制备了BEM/PMSQ杂化降凝剂。以青海含蜡原油为研究对象，通过流变实验评价了BEM/PMSQ杂化降凝剂对原油的凝点、黏弹性、黏度与屈服值的影响，利用偏光显微镜观察了加剂前后原油蜡晶形貌的变化，并与单独添加BEM降凝剂的油样进行了对比。结果表明：不加剂原油凝点27.0℃；在相同的降凝剂加量下（100 μg·g^-1），降凝效果最好的是BEM/PMSQ 2%杂化降凝剂，可降低原油凝点19.0℃，相较于添加BEM降凝剂，进一步降凝6.0℃，降低胶凝点4.3℃，10℃时平均降黏率39.0%，G'值降低了62.0%。PMSQ微球与BEM/PMSQ杂化降凝剂在十二烷中的分散状态照片表明PMSQ微球表面吸附了BEM降凝剂，从而在原油中作为蜡晶的成核模版存在，使所形成的蜡晶结构更为紧凑，包覆更少的液态油，从而改善原油的宏观流变性。

关键词: 降凝剂, 含蜡原油, BEM, PMSQ, 流变性

CLC Number:

TE832

SHI Xin, MA Xiaobin, YANG Fei, LI Chuanxian, YAO Bo, SUN Guangyu. Effect and mechanism of BEM/PMSQ hybrid pour point depressant on Qinghai waxy crude oil[J]. CIESC Journal, 2017, 68(8): 3014-3022.

史鑫, 马晓斌, 杨飞, 李传宪, 姚博, 孙广宇. BEM/PMSQ杂化降凝剂对青海含蜡原油作用效果及其机理[J]. 化工学报, 2017, 68(8): 3014-3022.

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