Pour Point Depressant Selection For The Third Dingjing Crude Oil Pipeline And Study On Factors Influencing Pour Point Depression Effects

The third Dingjing oil pipeline is designed for crude oil of Yanchang Petroleum Group.It is still in the design stage and has not been constructed.According to the preliminary observation and experimentation,the crude oil in the third Dingjing oil pipeline has high pour point and poor low-temperature fluidity,so pour point depressant(PPD)is added into the crude oil to guarantee the safety and efficiency of transportation at low temperature.Pour point depressant is not useful for any crude oil,so it is indispensable to select PPD for the certain crude oil.Before selecting PPD,pre-process the crude oil in the third Dingjing oil pipeline and measure the resin content,asphaltene content,wax content of oil.Then,select the most suitable pour point depressant,the optimal concentration of PPD and the best treatment temperature for the crude oil in the third Dingjing oil pipeline by comparing the pour point of oil under different treatment conditions.It is found that the density of crude oil in the third Dingjing oil pipeline is declined to some extent.After selecting the best treatment conditions,study the rheological property of oil before and after treated with PPD,and find out the wax precipitation point and abnormal point.It is found that the abnormal point goes down,which means the low-temperature fluidity of oil is improved.However,the pour point depression effects of waxy crude oil with PPD are affected by high-speed shearing,low-speed & long-time shearing,stewing,repeated heating and cooling rate.To ensure the safety and stability of pipeline,take pour point and apparent viscosity as reference standards,study the influences of these factors,and analyze the causes of experimental results.Stability experiment indicates that the short-time& high-speed shearing under higher temperature will improve the pour point depression effect of oil beneficiated with PPD;the effect of long-time& low-speed shearing is small;the deteriorated severity orders of the pour point depression effect of oil with PPD from big to small is stewing at 35?,stewing at finish cooling temperature and stewing at 25?;the effect of repeated heating depends on its initial temperature and finishing temperature;the apparent viscosity of oil treated by static cooling is bigger than that of dynamic cooling.