Research On The Effect And Mechanism Of Chemical Additives On Colloid System Of Caoqiao Heavy Oil

Heavy oil has large relative density and high viscosity.Due to its poor liquidity,it brings great challenge to mining and transportation.And adding oil-soluble amphiphiles is a feasible technology of improving heavy oil pipeline transportation efficiency and safety.This paper studied the effect of chemical additives of the small molecule and copolymer types on the colloid system of Caoqiao heavy oil,and revealed the laws of chemical additive's effect on associating structure and viscosity of heavy oil.It finally established the link of micro structure and macro flowability of Caoqiao heavy oil.The effects of amphiphiles of four types,alkaline,acidic,Bolar and Gemini,on associating structure and flowability of Caoqiao heavy oil were investigated through DSC analysis,viscosity-temperature test,conductivity measurement and particle size analysis.Experimental results show that the alkaline alkyl amines act as asphaltenes flocculants,decreasing the conductivity of heavy oils and flocculating asphaltene aggregates into larger units,which causes the obvious decrease of heavy oil viscosity.Dodecyl benzene sulfonic acid and 1,2-benzenedicarboxylic acid,dioctadecanamide of Gemini type perform as asphaltenes dispersants,bringing up the conductivity for heavy oils and dispersing asphaltene aggregates into smaller units,resulting in the significant increase of heavy oil viscosity.In addition,ethylenediamine and sebacic acid of Bolar-type amphiphilies can not only flocculate asphaltenes particles into larger ones,but also self associate into large amounts of polar micelles in heavy oil thus greatly enhancing the efficient polar fractions,which causes the increase of heavy oil conductivity and viscosity.The asphaltenes dispersion ability of dodecylaniline of alkaline type,lauric acid and dodecylphenol of acidic type is limited in the heavy oil,and do not significantly change the conductivity and viscosity of heavy oil.Copolymer additives were synthesized by radical polymerization.And the characteristics of synthetic products were represented by FI-IR,DSC,1H NMR and GPC.The effects of copolymer amphiphiles on associating structure and flowability of Caoqiao heavy oil were investigated through viscosity-temperature and conductivity tests.The experimental results show that due to the weak polarity of PA18,it needs to be compounded with surfactant molecules of strong polar functional groups that can break up asphaltene association structure to reach a certain influence of reducing viscosity.Due to the presence of polar functional groups of binary polymers acrylic ester 18-styrene,such as benzene,they can form strong ?-?and hydrogen bonding to penetrate and divide asphaltene layers,and they make a significant increase in conductivity of Caoqiao heavy oil,so they have better effects of reducing viscosity.However,binary polymer,crylic ester 18-maleic anhydride,has strong polar group of maleic anhydride,so they can reduce the conductivity and little increase the viscosity of heavy oil.And the ternary polymers do not have large influence of dispering asphaltene associating structure and can not change the viscosity of Caoqiao heavy oil significantly.