Study On The Measuring Method For Colloidal Stability Of Heavy Oil

The heavy oil colloidal stability deterioration brings a series problems in the processes of exploitation,transportation,production and refinery.The colloidal stability of heavy oil has a direct relationship with the asphaltene association or coagulation.So it is meaningful to study the relationship between asphaltene association or coagulation and the colloidal stability of heavy oil.A new method which is based on the property difference between upper and lower zone in a vessel to characterize the colloidal stability of heavy oil is proposed,including capacitance?conductivity?viscosity?density and ultrasonic methods.These methods are used in the stable and unstable oil samples which are added in solvents to dilute to study whether there are significant differences between the upper and lower zone.The oil sample MR AR and Oil Sand Asphalt are selected to study and the suitable experimental conditions of the differences between upper and lower are studied.For the differences of capacitance,the plates frequency is 1KHz?the temperature is 60 ? and the electrode space is 20 cm.The conditions for the differences of conductivity is the same as capacitance expect the temperature is 40?.For MR AR,it's unstable oil when the differences of capacitance reach 40% or the differences of conductivity reach 27%.Although for Oil Sand Asphalt,it's unstable when the differences of capacitance reach 12% or the differences of conductivity reach 6%.The colloidal stability of MR AR and Oil Sands Asphalt during the process of thermal reaction under the environment of nitrogen is also studied in order to do the online research of the upper and lower differences.The result is that the differences of conductivity between the upper and lower are the biggest when the electrode plates frequency is 100 KHz.When the differences reach 20%,it will start to coke.In addition,with the result of the differences of capacitance and conductivity between the upper and lower about the oil after thermal reaction,the suitable experimental conditions of the differences of capacitance are that the temperature is 100? and the electrode plates frequency is 1KHz while the conditions of conductivity are that the temperature is 40? and the electrode plates frequency is 100 KHz.The difference of conductivity between the upper and lower of the MR AR which underwent 3.5h thermal reaction with the environment of nitrogen is about 24%.And the differences of capacitance and conductivity of Oil Sands Asphalt which is under the same condition are about 32% and 15%.In addition,the differences of density?viscosity and ultrasound are also studied.The difference of density between the upper and lower of Oil Sands Asphalt which is diluted by solvent at the asphaltene coagulation point is 8%,and the difference of viscosity is 15%.The difference of ultrasound between the stable and unstable sample in velocity and ultrasonic attenuation is small,but it needs further exploration.