Study On Rheological Properties Of Mixed Crude Oil And Additive Operation Scheme Of Su Cuo Pipeline

Su cuo oil pipeline is mainly responsible for the task of transporting the crude oil of Hulun Buir oilfield,but it is keeping low throughput operation in recent years because of the oil field production declined.The production of Tamtsag oilfield,which belongs to Haita basin as the same,increased year by year,but it lacks of effective means of transportation.In view of this,Su cuo pipeline adopts mixed transportation of the Hulun Buir and Tamtsag crude oil at present.The differences between chemical composition of two kinds of crude oil causing great changes of rheological properties of mixed crude oil,which increasing the difficulties of pipeline operation and management.Therefore,it is necessary to study on the rheological properties of mixing crude oil in different ratio of the Hulun Buir and Tamtsag crude oil,Optimize the best pour point depressant and suitable conditions for the mixed crude oil,which can effectively reduce the energy consumption of oil under the premise of ensuring the safety of the pipeline transportation.Specific research work is as follows:Firstly,test the viscosity and yield value of mixed crude oil using rotational rheometer.On the basis of test results,modify single logarithm model which is optimized and suitable for prediction of mixed oil viscosity modification using the least square method and establish viscosity calculation model of mixed crude oil which is applicable to Su cuo pipeline.The minimum absolute deviation of the correction model is 0.59%,and the maximum absolute deviation is 3.63%.Measure the pour point of mixed crude oil by pour point testing instrument,and modify Liu Tianyou model using the least square method.Compared with the original,the average absolute deviation of the modified pour point model decreases by74.49%,and the maximum standard deviation decreases by 75.26%.The thermal characteristic parameters of mixed crude oil were tested by differential scanning calorimetry.Wax point,wax precipitation peak temperature and other related experimental results of different mixing ratio crude oil can be obtained.Secondly,the mechanism of pour point reduction of waxy crude oil was discussed in depth,analyze the factors that influence the modification effect of pour point depressant and eight kinds of pour point depressant were screened.According to the experimental data,set the pour point as the first criterion,and the viscosity reduction rate as the second,so as to select the best pour point depressant,and further study shows that the optimum additive temperature is 70 ?,and the optimum dosage is 600 ppm.Experiments show that the maximum drop of pour point of the mixed crude oil is 11 ?,and the average viscosity reduction rate is 86.01% under the temperature of 25?.On this basis,the modification effect of pour point depressant was evaluated indoor,and the stability of additive crude oil under repeated heating,high speed shearing and long standing condition was discussed.Finally,based on experimental results,combined with the actual operation condition of the pipeline,thermal properties,hydraulic characteristics and the oil cost which run in winter under different throughput are analyzed.Set the minimum pipeline total energy consumption cost as the goal,get the optimal operation scheme at different throughput of the pipelineunder the condition of considering adding pour point depressant,which provide theoretical guidance with the production and management of the pipeline.