Study On The Viscosity Reduction Behavior And Asphaltene Stability In Diluting Heavy Oil

The exploitation of poor-quality heavy oil is gradually replacing that of high-quality light oil because of depletion of conventional crude oil reserves.As difficult exploitation,transportation and processing of viscous heavy oil with high asphaltene content,it is very important to study viscosity reduction behavior and asphaltene stability in heavy oil dilution.The asphaltene stabilizers with different characteristics and different functional groups such as polyisobutylene succinimide benzoic acid and 3-(2-hydroxy-alkyl)amino phenylboronic acid were synthesized,in order to investigate the effect of asphaltene stability on viscosity reduction of Canadian oil sand bitumen with high content and high polarity asphaltene.The synthesis conditions such as reactant molar,reaction temperature,reaction time,alkyl chain length and functional groups with polarity were investigated and optimized by analyzing the effect of asphaltene stabilizers on asphaltenes stability with the methods of polarized light microscopy,UV-Vis spectrophotometry,rheology and static observation.3-(2-hydroxy-hexadecyl)aminophenylboronic acid and polyisobutylene succinimide phenylboronic acid had the best stable efficiency up to 90%on asphaltenes in Canadian oil sand bitumen.Newtonian fluid was obtained as two asphaltene stabilizers mixed with oil sand bitumen and n-decane oil sample.The effects of different chain length alkanes,different polar aromatic diluents,and synthetic asphaltene stabilizers on viscosity-temperature,rheological properties and rheological-oscillatory properties of heavy oils were analyzed by rheology.When all the diluents were added at a mass percentage of 10%,the mixed oil sample had a characteristic of newtonian fluid at about 35°C.When the ratio was greater than 15%,the n-decane diluent had the best viscosity reduction effect and the viscosity reduction efficiency is 98.96%.The bridging connection of two polar groups of asphaltene stabilizers with asphaltene gave descending order of viscosity reduction effect for ethanol,ethylene glycol and ethanolamine in turn,making the asphaltenes form a spatial network structure and affect the viscosity reduction.the elastic modulus G?and the viscous modulus G?of the mixed oil sample with the polar group diluent was measured and the result showed that the elastic modulus was always smaller than the viscous modulus,and the difference value became more remarkable as the strain became larger,so that the mixed oil behaves as a fluid viscosity characteristics.The effects of different types of solvent oils and simulated condensate and synthetic oils(Syn)on the rheological properties and viscosity of heavy oils were investigated.The viscosity of the oil sand bitumen mixed oil sample with 30%synthetic oil(Syn)was reduced by 99.5%compared with that of the pure oil sand bitumen;The increase of naphthenic components in Syn had reduced the effect of viscosity reduction,and increasing the content of aromatics in Syn,the effect of viscosity reduction increased.The 150~#solvent oil had a significant viscosity reduction effect to Canadian oil sand bitumen.The mixing solvent of150~#and 200~#solvent oil had a viscosity reduction efficiency of 99.83%.