陕北地区混合原油流变性及其添加降凝剂输送技术实验研究

Experimental Study on Rheological Properties of Mixed Crude Oil in Northern Shaanxi and Its Transportation Technology with Added Pour Point Depressants

由于陕北地区各地方原油物性和流变性均有差异,且陕北地区四季昼夜温差变化较大,导致原油管道输送中摩擦阻力增大,管道内腐蚀、内磨损严重,不安全、不节能、不经济事件频发,因此,对陕北地区原油物性和流变性进行长期实验研究非常必要。选取陕北延安地区的吴起、永宁、西区、下寺湾四个油区混合原油为对象,采取实验法、比较法、筛选法对四个油区混合原油组成、物性、热处理、加降凝剂及其改性等方面进行实验研究。结果表明:混合原油属于轻质含蜡原油,其热处理效果明显,当加热温度在45~60℃范围内时,凝点最高为22~24℃;当热处理温度在65~80℃时,混合原油的凝点最低可至13℃,降幅可达11℃。通过实验筛选,混合原油添加GY3型降凝剂运行效果比添加其他类型的降凝剂效果好,最佳添加浓度为50 mg/kg,最佳热处理温度为65℃,混合原油的凝点由24℃降到9℃,反常点由27℃降到18℃,低温下黏度也有大幅度降低;混合原油最低允许重复加热温度≥55℃。实验结果揭示了陕北地区混合原油物性、流变性、热处理、加降凝剂等变化规律,给含蜡混合原油管道低输量运行制定了新工艺技术方案,对吴起至延炼原油管道安全、平稳、经济运行及今后再建复杂管网有指导意义。

The physical properties and rheological properties of crude oil in the Northern Shaanxi region differ from place to place.In addition,the difference in temperature between day and night in the four seasons in the Shanbei region varies greatly,which leads to the increase of friction resistance,and serious corrosion and internal wear in crude oil pipeline transportation,unsafe,non-energy-saving,non-economic and other frequent incidents.Therefore,it is necessary to study the physical and rheological properties of crude oil in the Northern Shaanxi area by long-term experiments.The mixed crude oil from Wuqi,Yongning,Xiqu,and Xiasiwan oil regions in the Yan'an region of the Northern Shaanxi area is selected as the target.This study mainly adopts experimental method,comparative method,and screening method to conduct experimental research on the composition,physical properties,heat treatment,addition of pour point depressants,and their modifications of the mixed crude oil from the four oil regions.It is concluded that the mixed crude oil belongs to light waxy crude oil.Its effect of heat treatment is obvious,when the heating temperature is in the range of 45~60℃,its pour point is the highest,which is 22~24℃.When the heat treatment temperature is in the range of 65~80℃,the minimum pour point of the mixed crude oil can reach 13℃,and the decrease is up to 11℃.The effect of GY3 pour point depressant added into mixed crude oil is better than that of other types of pour point depressants.The optimum adding concentration is 50 mg/kg,the optimum heat treatment temperature is 65℃,and the pour point of the mixed crude oil is reduced from 24℃to 9℃,the abnormal point decreased from 27℃to 18℃,and the viscosity also decreased significantly at low tempera-tures,the minimum allowable reheating temperature of mixed crude oil is 55℃or more.The experimental results revealed the changing law in physical properties,rheology properties,heat treatment,and addition of pour point depressants of mixed crude oil in northern Shaanxi.This provides a new process technology plan for the low-throughput operation of waxy mixed crude oil pipelines,and has guiding significance for the safe,stable,and economic operation of the Wuqi-Yanlian Crude Oil Pipeline and the future construction of complex pipeline networks.