采用降凝剂改善多蜡原油低温流变性研究

IMPROVEMENT OF FLOWABILITY OF A WAXY CRUDE OIL UNDER LOW TEMPERATURES BY POUR POINT DEPRESSANTS

进行了多蜡原油添加降凝剂处理的实验研究。探讨了降凝剂的应用条件,考察了处理温度、冷却速度、再次加热、高速剪切、生油掺合、降凝剂注入量等因素对降凝改性效果的影响。得到的主要结论有:①加降凝剂时的处理温度有一最佳值;②在析蜡点以上10℃再次加热对流变性影响甚微,降凝改性后的原油在温度回升时出现性能恶化区;③流变性的改善随降凝剂注入量的增大而趋于一极限值。

The flowability of Malin-Huian pipeline waxy crude oil, Changqing Oil Fields, under low temperatures is studied as influenced by pour point (p·p·) depressants, a combination of two US commercial chemicals C8806+C8361 in ratio 1:1. The effects of various factors on rheologic and thermal characteristics of the treated oil are investigated and following conclusion are made. ( 1 ) There exists an optimum temperature for treating crude oils by p·p· depressants and for the oil under study the optimum thermal treating temperature is 85℃, followed by rapidly cooling to lower than 15℃ at a cooling rate of 0.3—0.5℃/min.Pour point of thus treated oil is decreased from 16℃ to —7℃, viscosity at 5℃ and 11.5s^(-1)—from 1363 to 53.2mPa·s, yield stress-from 63.4Pa to null, abnormal point—from 24℃ to 12℃. (2) With increasing the use level of p·p· depressants the improvement in flowability enhances and eventually reaches a limit.(3) When reheated from low temperature, the flowability of the chemically-thermally treated oil deteriorates at temperature range 15—50℃ with the peak near 25℃ and recoveries gradually above 50℃.