Study On The Colloid Properties Of Super-heavy Oil

Heavy crude oil will cover a larger proportion of petroleum trade in our country with the consuming of light crude oil. The super-heavy crude oil with viscosity above 100000 mPa·s is the most typical one. No mature study methord has been developed home and abord because of its higher viscosity, bigger density and higher content of resin and asphaltene. Most of the study are about its displacement mechanism.Study of its colloid properties for such kind of reservoirs are in urgent need in order to find reasonable producing and fining technology.In this paper,based on the colloidal structures theories of heavy crude,the microscopic nature, colloidal properties and the macroscopic properties of the eight Super-heavy oil samples were studied systematicly and comprehensively, and the relationship among them were explored.On this basis, the effect of additives on the viscosity, or physical and chemical properties of the super-heavy oil were studied.The macroscopic properties of heavy oil includ the fraction composition, properties and mean structures of fractions.The mean dipole moment values of fractions were computed from the data of molecular weight, dielectric constant and refractive index. On this basis, the element composition and mean structure were also studied. The results showed that the aromatic ratio, heteroatom and metal contents contribute to the high polarity of the asphaltenes. This is the basis of other properties of heavy oil.Viscosity is the basic parameters reflecting the rheological properties, and colloidal stability is the basis of colloidal dispersion. The Brookfield rotary viscometer was used to measure the rheological properties, and Mass Fraction Normalized Conductivity method was used to study the colloidal stability of samples. The fraction composition and properties of fractions were studied to explore the factors impacting the viscosity-temperature properties and colloid stability. It can be concluded that the fraction characteristics and content paly the decisive role in the viscosity and colloidal stability of super-heavy oil. The samples with greater heavy components have greater viscosity value, and the samples with high contents ratio and high properties Intermateability of resins and asphaltenes have the greater value of colloidal stability. Additives, high temperature steam and CO2 are effective methods to reduce the viscosity. The viscosity property and colloidal stability variation of samples with or without additive were studied. Fourier transform infra-red spectrometer, the synchronous fluorescence spectumeter and the Zetasizer Nano ZS particle size analyzer were used to analyse the effect of addictives on the asphaltenes. The results showed that the effect of addictives on the asphaltenes is strong and the reduce of the viscosity is achieved by the changing of the asphaltenes'particle size. In addition, the viscosity-reducing effect of high temperature steam and CO2 is achieved by breaking asphaltenes'alkyl-side-chain and by changing micellar structure.