Study On Synthesizing Pour Point Depressant For Crude Oil

Most of oilfield in our country yield high waxy crude oil, in which paraffin content is about 20%, even reach to 40%, which caused it difficult to exploitation and transportation. The method of adding pour point depressant (PPD) can be used to solve this problem. Wax crystal configuration can be modified by PPD, and it is difficult to form three-dimensional network structure at normal temperature, so the pour point can be depressed.The object of this thesis is to synthesize and select the PPD which is more effective . Firstly, a series of PPD were synthesized, which were polymerized with different monomers. The more effective PPD, AMS (Octadecyl acrylate-Maleic anhydride-Styrene) and AVS (Octadecyl acrylate-Vinyl acetate-Styrene), were selected by testing the ability of depressing the pour point of Daqing crude oil, and then the synthetic condition of the two PPD were discussed. The combination of AMS or AVS with EVA was studied. By orthogonal test, the optimal synthetic condition of AMS was determined as follows: when the temperature of the reaction was 90℃and the reaction time was 7h, the best molar ratio of A, M and S was 9﹕1﹕1, the dosage of initiator was 0.5%; The optimal synthetic condition of AVS was determined by conditional experiment: when the reaction temperature was 90℃and the reaction time was 7h, the best molar ratio of A, V and S was 8﹕2﹕1, the dosage of initiator was 0.6%.Combinating AMS and EVA in different mass ratio could reduce pour point of Daqing crude oil by 10℃, and the pour point of Jilin and Shencai crude oil was decreased by 9℃and 3℃respectively; AVS and EVA combinated in different mass ratio could reduce pour point of Daqing crude oil by 9℃, and the pour point of Jilin and Shencai crude oil was decreased by 10℃and 4℃respectively.AMS-EVA and AVS-EVA could depress wax precipitation temperature and abnormal point of Daqing, Jilin, Shencai crude oil. The two types of PPD could also reduce the viscosity of the three kinds of crude oil and improve the rheological properties of them at low temperature.