Selecting And Evaluation Of Depressant Of Oil Transported By Sino-Kazakhstan Oil Pipeline In Alashankou Port

This paper takes the oil in Sino-Kazakhstan oil pipeline of Alashankou port to reduce the pour point and viscosity of crude oil to improve cold flow properties of crude oil as research subject, and does a selecting evaluation research about the six common used depressants.(1) After six-month detecting of the fundamental oil materials in Sino-Kazakhstan oil pipeline of Alashankou port, which covers the daily oil density, Pour point, salt content, sulfur content and water sediments, and with the monthly collected data analyzed, the sample oil with the highest monthly pour point from September to Decemember is selected as the depressant oil. We also tested some Physical properties such as Freezing point, initial lutetium point, wax content, wax point, abnormal point, etc.(2) For the four selected oil, with the same temperature and dosage amount, decrease the temperature of the sample oil to the testing temperature with the speed of 0.5℃/ min ~ 1.5℃/ min.the oil sample pour point depressant is screened by testing the changes in viscosity and pour point under different shear rates.Separately add one of the six depressants to do the selecting experiment to the four selected oil and finally reaches that Depressant B (EVA) is the best of the four. In addition, the best dosage density is 50mg/kg. With the 50mg/kg depressant B, the best operation temperature is 60℃.(3) Add the 50mg/kg depressant B at 60℃, with the testing temperature of every sample oil, we made the Viscosity-Temperature curve for different shear rate before and after adding the dosage. Besides, we did comparison for viscosity-temperature curve, fitting the relevant flow equations at different temperatures to analyze. The results show that the pour points of four oil samples decrease more than 10℃, abnormal point reduction ranges from 2℃~ 6℃, oil stick is reduced significantly, Newtonian fluid regions is widened and the mobility of crude oil is significantly enhanced .(4) 50mg/kg depressant B is added at 60℃, at different testing temperatures of sample oil, we reheated the sample oil, and also did high-speed shear and static stability experiment. When reheating temperature approaches the peak temperature of crude oil wax precipitation, the viscosity of crude oil rebounding liquidity worsens; Similarly, high shear in the vicinity of the abnormal point makes the liquidity of crude oil worse; four oil samples all have good static stability.(5) We did some basic studies about the depressant and economic benefits mechanism of the selected depressant B.