Preparation And Properties Of Composite Heavy Oil Viscosity Reducer

The heavy oil resources are abundant in China.However,high viscosity,high density and poor flowability of heavy oil have brought much more difficulties than conventional crude oil does in transportation.In this thesis,aimed at the characters of the heavy oil(viscosity:3000-10000 mPa·s),a kind of effective viscosity reducer,with good ability to decrease the viscosity and improve the fluidity of heavy oil,had been synthesized.We tested and analyzed the constituents of heavy oil sample from Zhundong oil base in Xinjiang.The results showed that the contents of the resin and asphaltene,polarity of groups and aromatic ring structure arrangement played a significant role in determining the high viscosity of heavy oil.Meanwhile,these results provided a theoretical basis to design and synthesize an effective viscosity reducer.Firstly,the octadecyl acrylate was prepared via a direct esterification method,in which the effecting factors on the quality of the product were investigated.The approprite synthesis conditions were obtained as follows:the monomer molar ratio of acrylic acid and octadecyl alcohol was 1.2:1.The dosage of p-toluene sulfonic acid was 1.2%.The amount of hydroquinone was 0.7%.Reaction temperature was 120? and reaction time was 5h.And then an oil-soluble terpolymer viscosity reducer SSA was synthesized from styrene,acrylic acid and the prepared octadecyl acrylate.The optimum experimental conditons were obtained as follows:the monomer molar ratio of octadecyl acrylate,styrene and acrylic acid was 8:2:1.The dosage of initiator was 1.0%.The polymerization temperature was 80? and the reaction time was 6h.The viscosity reduction rate was 32.2%when the dosage of viscosity reducer was 700 mg/L at 50 ?.In order to enhance the viscosity reduction rate,the polypropylene glycol caprylate was synthesized,in which the effecting factors on the quality of the product were investigated.The optimal reaction conditions were obtained as follows:the monomer molar ratio of n-caprylic acid and polypropylene glycol was 1.4:1.The dosage of p-toluene sulfonic acid was 1.5%.Reaction temperature was 110? and reaction time was 5h.A composite system with the combination of copolymer and polypropylene glycol caprylate exhibited excellent performance in reducing the viscosity of the heavy oil.When the mass ratio of SSA to PO was 6:4,and the dosage of viscosity reducer was 800 mg/L,the viscosity reduction rate was 41.8%.The composite viscosity reducer had the dual effects of viscosity reduction and demulsification.The moisture content was higher,the effect of viscosity reduction was better.The composite viscosity reducer has been applied to the heavy oil from Jimusar oil in Xinjiang.The highest viscosity reduction rate was 43.0%when the mass ratio of SSA to PO was 5:5.By comparing the two kinds of heavy sample,the heavy oil of different fields showed different compositions and properties.When using the viscosity reducer,the compatibility problems of heavy oil and viscosity reducer should take into consideration.Lastly,the mechanism of viscosity reduction by adding viscosity reducer was discussed detailedly.The viscosity reducer could penetrated and disrupted the stacked body of colloid and asphaltene.Through hydrogen bonding interaction,the dispersity of the system was inhancive.