Research On Wax Deposition Of Qing-Russian Mixed Crude Oil

Today,oil is not only a non-renewable energy source,but also a strategic energy source that countries need to survive and remain strong.Petroleum products can be transported not only by sea,land and air,but also by oil pipelines.Oil pipeline buried in the ground,along the fiber optic cable,the pipeline transportation is convenient and fast,the transportation volume is large,and the anti-corrosion effect is better.However,when the pipeline transports waxy crude oil all year round,due to the existence of objective factors such as temperature difference,pressure and time,wax deposition will gradually form,bringing security risks to crude oil transportation.The northeast pipe network is located in the northeast of China,with low geological temperature.Daqing crude oil is high in wax oil,so the wax deposition problem is more serious.In recent years,due to the decrease in output of pipeline oil fields in northeast China,in order to meet the actual needs of pipeline transportation,qinghai-harbin pipeline will mix the imported light Russian oil and domestic high-viscosity crude oil in proportion to make up for the shortage of production capacity.At the same time,this practice can play the role of dilution and viscosity reduction and drag reduction,reducing the huge energy consumption caused by traditional heating transportation.However,daqing crude oil is different from rosneft in various aspects,which is obviously reflected in rheological properties and wax deposition characteristics.In view of the above practical situation,this paper established a cold finger experimental device,and discussed the wax deposition rule and its influencing factors when the proportion of rosneft was 20%,30% and 40% under different experimental conditions.The molecular diffusion coefficient formula after the mixing of two crude oils was put forward,and the following conclusions were obtained:(1)The wax evolution point,abnormal point and loss point of the four oil samples all decreased with the increase of the mixing amount of Russian oil.The same oil,the shear rate is constant,the higher the temperature,the lower the viscosity.The temperature and shear rate were constant,and the viscosity of the four oils decreased with the increase of the mixing amount of Russian oil.(2)A differential scanning calorimeter was used to study the characteristics of oil sample wax extraction.The wax extraction point,wax extraction peak and wax content of the four crude oils all decreased with the increase of the mixing amount of Russian oil.According to the observation by polarizing microscope,the number of wax crystals and the integral number of wax crystal surface decreased with the increase of the mixing amount of Russian oil,and the wax precipitation point decreased gradually.(3)According to the cold finger experiment,the longer the time,the stronger the aging effect,the harder the sediment,and the lower the deposition rate;When the hot bath temperature is constant,the cold bath temperature increases,the wax deposition quality and the wax deposition rate decrease,and the sediment is soft.When the temperature of the cold bath is constant,the temperature of the hot bath increases,and the wax deposition becomes hard.When the temperature difference is the same and the temperature range is different,the deposition quality and the deposition rate decrease with the increase of the temperature range.When the oil samples are different,the deposition quality and the deposition rate decrease with the increase of the mixing amount of Russian oil,and the precipitate becomes soft gradually.